Scotrail has warned travellers to expect cancellations after it was unable to publish a temporary Sunday timetable in the face of ongoing driver shortages.
The railway operator - which is now under public ownership - announced via social media that it could not guarantee all services on Sunday would go ahead as planned.
Train bosses are battling staffing shortages in the wake of the coronavirus pandemic. The shortages have led the firm to clashes with trade unions who say existing drivers are being overworked.
A third of Scottish railway journeys - 700 a day - have been slashed from timetables across the country, with some stations not being served beyond 7pm.
Scotrail said on Twitter on Saturday: "Unfortunately, it hasn’t been possible to implement a temporary timetable for tomorrow [Sunday].
"That means the normal Sunday timetable will be in operation and there will be cancellations as a result."
David Simpson, Scotrail's service delivery director, said: "Unfortunately, it has not been possible to publish a temporary timetable for this Sunday. That means the normal timetable will be in operation, however, there will be cancellations as a result.
“The complexities of pulling together such widespread changes to timetables means that it's not possible to do so in such a short space of time.
“We apologise to customers and advise them to check their journeys before travel.”
The potential chaos awaiting train travellers on Sunday is the latest in a line of headaches for the railway operator, which entered public ownership on April 1 this year.
It has been asking drivers to cover more shifts to make up for a shortfall of around 130 drivers that it says would have been trained up and piloting locomotives were it not for the coronavirus pandemic.
However, trade union Aslef says Scotrail is asking too much of its existing drivers and along with the RMT is balloting on potential industrial action.
Aslef called a proposed 2.2 per cent pay rise for drivers "neither fair nor reasonable" and wants to see employees offered an inflating-matching rise of 10 per cent.
Scotrail has since come back with a 4.2 per cent pay rise offer that unions will put to members next week.
But while the dispute rumbles on, drivers are refusing to cover overtime or work on rest days, putting strain on the network and prompting the operator to cut services.
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Scotrail introduced a new "temporary timetable" earlier this week with fewer services, which was initially criticised for not serving lines later in the day.
Trains running as late as midnight were later factored into the timetable and will continue to do so while the dispute continues.
Scotrail has already agreed to overhaul its refund policy to accommodate its new regime, dropping admin fees for journeys that it has cancelled.
There are concerns that the disrupted timetable will affect events such as Scotland's World Cup qualifier against Ukraine on Wednesday.
Under the current temporary timetable, trains from nearby Mount Florida station cease at 8.46pm - nearly an hour before the full-time whistle blows.
But even if an agreement is reached it may take up to 10 days for a full timetable to be reintroduced.
Simpson told the BBC's Good Morning Scotland on Friday: "It's a complex process and involved all parts of the industry changing rosters, and we would need to do that as quickly as possible, but it could be up to 10 days to get fully back to normal.
"We are also reviewing the current timetable and we have added some more late-night services for tonight and tomorrow night and looking to the football on Wednesday - Scotland versus Ukraine - to do more there.
"We are trying to be as flexible as possible until we can get the full timetable back."
Transport Minister Jenny Gilruth told MSPs on Thursday the Scottish Government wanted to find a solution in a "timely fashion".
The SNP minister added: "I am absolutely committed to working with our trade unions...to ensure that public ownership is a success for our railways and that we re-establish the previous timetable to allow passengers to travel more freely.
"I want nothing more than for us to restore the previous timetable that was in place. Passengers need certainty."
Scotrail said previously: "We're aware how much recent disruption has been affecting our customers and believe introducing a temporary timetable will provide greater certainty and reliability for those travelling.
"We want to resolve this dispute with the trade unions and move forward together to provide the safest, greenest, and most reliable railway we can for Scotland."
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