Children have been stuck in coaches "with no food, water or toilets" for hours on end as severe delays continue at Dover.
Extra sailings were run overnight to try and clear the backlog, as some parents said their kids were being held for up to 18 hours.
But this morning, the port estimated some travellers could still face waits of up to eight hours, depending on the ferry operator.
A port spokesman said: "The additional sailings have assisted in clearing some of the traffic, although currently both DFDS and P&O have two full lanes of coaches in the port before French border controls, with a processing time of about 4.5 hours.
"P&O have some coaches waiting at the cruise terminal and DFDS have some at service stations in Kent.
"Once coaches are processed in an operator's lane, more are being sent to the port. Currently, the estimated total time is six to eight hours dwell time."
At around 7am today, one teacher waiting with a coach full of 42 children labelled the conditions as "disgusting", saying they had no water, food or toilets since arriving at the port.
And Gillian Charlton, 43, said her 13-year-old son, Ned, and his friends have been in a holding area since arriving at around 7.30pm last night.
She said the children are only allowed to get off to use a portaloo and were given one KitKat at midnight.
Meanwhile, another school was forced to cancel their ski trip altogether after being told to wait for a staggering 24 hours.
One disappointed parent, Louise, wrote: "This is horrendous my daughter’s school coach was called to the port this morning having waited there for 12 hours to be then told there is a further 12 hr wait!!
"They have had to give up, cancel their skiing trip and come home. A year of build-up for nothing."
And teacher Sarah tweeted: "An honest assessment of the situation would be nice. 42 kids, 12 hours since arriving at Dover, some of it at stop 24 still not at passport control.
"No water, no food, no toilets since getting to port and a child with a kidney condition it's disgusting."
Mum Gillian said her son waited for 14 hours before being moved up to passport control and has now been waiting for a further two hours – with no sign of movement.
The social care worker said: "It’s shambolic. I don’t think they have access to running water and can’t get off – only to use the portaloo.
"They were given a KitKat at midnight. Children are feeling unsafe. They are all starving."
She said her son had been really looking forward to the ski trip and the family had been saving up to make sure he could go.
Gillian said there are hundreds of coaches behind her son’s coach but cars are "flying through".
She added: “I’m disgusted. My son said there are hundred coaches behind them – and I think it’s mainly school kids.
"I sent him off with food for the day and they had breakfast vouchers to get food in France in the morning.
"I’m fuming. The fact that it’s mainly schoolchildren penned in... they should have restricted the bookings.
"They know how many people turn up at the ports. I’m so worried."
Another parent tweeted to ferry operator DFDS and demanded to know whether they would be providing her child with food or water.
Abbie said: "My child has been on a coach for 18 hours!! And only just in dock!! What is the wait time now until boarding? What are you doing to get coaches through?
"These kids have had no food. Will you be giving them food and water?"
A third asked P&O Ferries: "My son and a coach load of his friends plus their poor teachers have been parked up at an industrial estate since last night. No sign of moving. They were due to sail last night.
"What are you doing to help? This is absolutely abominable treatment."
Marc Mitchell-Miles, 47, said his daughter Lily set off from Weston-super-Mare at 3pm yesterday with school friends for a week long ski trip in Italy.
The party of 100 students - who are travelling on two coaches - arrived at the port at 8pm but have not moved since.
Father-of-two Marc said: "As parents we're terribly upset and worried that they're having to go through this and I can't be there to provide comfort and reassurance in person.
"We can't settle until we know what's going on. There is also the cost of the trip which they're going to be missing out on a sizeable chunk of.
"It cost around £900 for the trip, but then there is also spending money and ski lessons before going on top of this. We wanted this to be a memorable experience, but not for this reason.
"The coach left Weston-super-Mare around 3pm yesterday and arrived at 8pm last night. They have just been advised that it could be another nine-hour wait.
"They have not been given any food by the port. My daughter just spoke to me and said she and her friends have gone out to find and buy some sandwiches.
"They're tired from the journey up and have had zero sleep, and she feels like she just wants to come home and is quite teary.
"Lily missed her school camp in Year Six due to Covid and this was the first time she's been away without us, and has been a bitterly disappointing experience.
"We're not able to settle at home either because we don't know what's happening and if there's a plan to move things forward.
"The school have just posted some footage on Facebook and social media and the teachers look like they're doing their best to occupy the kids."
Meanwhile Cerie Bullivant, 40, has been stuck at the port with his wife and four young children for 10 hours, and said he had to walk 45 minutes into Dover to get food for his family.
The security officer said the queue for the women’s toilets at the port is "snaking round the building" and there doesn’t seem to be any access to free drinking water.
He said they have not been given any food by the port officers and have not received any updates on the current situation or wait times since arriving at the port at 2am.
Cerie, from South London, said: “We arrived at the port at 2am after taking the midnight coach from London Victoria.
“We were meant to get on a 10am ferry across to Amsterdam to see my wife’s parents and were looking forward to it.
“At the Dover port, the queue for the women’s toilets is absolutely awful. It has been snaking around the block all morning.
“The men’s toilets on the other hand have no queue like usual. We don’t seem to have any access to free drinking water and can’t find anywhere to fill up our water bottles.
“I have just come back from walking into Dover town centre to find my family some food. It was a 45-minute walk each way.
“At the port there is a small costa to provide for all the people here and all the vending machines in the port are completely empty.
“The worst thing is no one is telling us anything and we are not getting any updates. So far we have been able to keep the kids entertained with Netflix – thank Goodness for Netflix.
“And we have been bribing them to behave with sweets and treats. When I went to the P&O desk earlier to ask for an update, the lady on the desk didn’t know anything – which isn’t her fault.
“We would just like to get some kind of update on the wait time and ferry situation. The cars don’t seem to be having a problem getting onto the ferries as they have a separate lane to the coaches.
“It is the coach lane which is taking forever.”
P&O Ferries apologised to customers on Sunday, saying some will face waits of four to five hours.
The firm had also stated that coaches at the Cruise terminal were still facing a wait time of up to 3.5 hours before they can proceed to the Port of Dover.
It added: "Once they are in the buffer zone at the entrance to the port the wait is approximately another 3-4 hours. We apologise for delays."
The port spokesman said: "There is still the on-going situation at the Port but both DFDS and P&O are adding additional departures overnight.
"Vessels usually have a longer layover at night but they will be running back and forth to clear as much as they can.
"At present, we anticipate the backlog around lunchtime tomorrow but the extra sailings could well reduce that time."
Yesterday, a port spokesman said he was "deeply frustrated" as coach traffic faced "significant delays".
Additional coach bookings taken by ferry operators for Easter had impacted upon operations, a statement on the port's website said on Saturday morning.
Just before 9am, a spokesman for the port said: "Coach waiting time is still several hours, but tourist cars are getting through OK."
P&O Ferries also apologised for the wait times for coaches sailing from Dover, while DFDS advised passengers to allow extra time to complete border and check-in controls.
The port said food and drink had been provided to coach passengers in the queues, despite parents claiming otherwise on social media.
Traveller Rosie Pearson said it was "carnage" in Dover as she was stuck for 16 hours with her husband and two teenagers.
Ms Pearson, 50, is an environmental campaigner from Essex and was travelling to Val d'Isere in the French Alps on an overnight bus.
It was due to arrive at 2.15pm on Saturday, but they expected they would probably not make it until 6am on Sunday due to delays in Dover.
"The whole thing was a shambles... Not a single bit of communication," Ms Pearson said. "It was carnage. The worst thing was that no-one told us anything for the whole 16 hours, literally nothing.
"(We are) very tired but people are resigned now and relieved to be en route. Shocking that something this chaotic can happen.
"My children's school has a ski trip this week (they are not on it, with us instead) and their bus was turned away last night - they had to sleep at a service station and come back this morning."
Labour leader Sir Keir Starmer urged the Government to "get a grip" of the situation at Dover.
"I really feel for people trying to get through Dover. There will have been families who have booked holidays and now they are frustrated yet again and I think the nature of the frustration will be 'not again'," he said.
"This is not the first time there have been problems at Dover. The Government needs to get a grip of this.
"You can't have every summer holiday, every Easter holiday, the same old problem. And so the Government needs to get a grip on this and actually help people out, who are just trying to get away for a few days' holiday."
A Government spokesman said: "The UK Government remains in close contact with ferry operators, the French authorities, and the Kent Resilience Forum, regarding delays at the Port of Dover.
"The port has advised that it remains busy, but the situation has improved significantly since yesterday, with coaches being processed at a much quicker rate.
"We recommend passengers check the latest advice from their operators before travelling."
Port of Dover chief executive Doug Bannister blamed the delays on extra checks because of Brexit.
He said: "The difference of living in a post-Brexit environment means that every passport needs to be checked before a vehicle or passenger can pass through to the EU through France, and that happens here in Dover. So it does make processing more challenging."
But Home Secretary Suella Braverman denied Brexit was fuelling delays at Dover.
She insisted quitting the EU - meaning officials have to check passports for all coach passengers sailing to France - was not contributing to the chaos.
"No I don't think that's fair - (that) that has been an adverse effect of Brexit," she told Sky News’ Sophy Ridge On Sunday show.
"What I would say is at acute times when there is a lot of pressure crossing the Channel, whether that's on the tunnel or ferries, then I think that there's always going to be a backup and I just urge everybody to be a bit patient while the ferry companies work their way through the backlog.”
Denying such delays would hammer every school holiday getaway, she added: "I think we have got a particular combination of factors that have occurred at this point in time."
Naomi Smith, chief executive of international campaign group Best for Britain, told the Mirror: “This Government delivered a needlessly hard version of Brexit that it also spectacularly failed to plan for.
“Braverman can deny it all she likes, but the problems at Dover and elsewhere across the economy will persist until we rebuild ties with our closest neighbours in Europe.”
Shadow Levelling-Up Secretary Lisa Nandy accused ministers of failing to plan for what would happen after the UK left the EU.
Asked whether Brexit was a factor in delays at the Kent port, the Labour frontbencher said: "There are clearly a range of factors that have gone into the delays here and we've seen them before, But the Government has known for a very long time that they needed to make sure that there were resources in place to deal with additional paperwork checks.
"The point is not whether we left the European Union or not; the point was that we left with a Government that made big promises and once again didn't deliver.
"And I really feel for the families that are trying to get away for an Easter break, people who have been caught up in this chaos, people whose livelihoods are threatened."
