Vladimir Putin’s forces could try to starve Ukrainians and “crush” their resistance, the country’s ambassador has warned.
Kyiv’s envoy to Britain, Vadym Prystaiko, gave a bleak assessment of the six-day-old war launched by the Russian president.
He warned Ukrainians were struggling to access cash as Kremlin forces encircled major cities.
Asked about the potential for a “food crisis” and looting, the diplomat told the Commons Foreign Affairs Select Committee: “They will try to crush the will of the Ukrainian people to resist.
“We see problems with cash for example - people just running out of cash and they have interruption in their services.
“The terminals won’t be working and we will have to come up with some military solution to the distribution of food.”
It comes as Latvia's Deputy PM warned that Putin could apply tactics similar to Syrian President Bashar al-Assad against his own people.
In a grim Commons hearing, Mr Prystaiko told MPs that Ukraine had to “pump up all the food we can until the routes are blocked”.
Mr Prystaiko described the humanitarian plight facing citizens who bravely opted to remain in major cities like Kyiv and Kharkiv rather than flee.
“These people have to be fed and so far they have everything - they have communications, they have electricity, they have water,” he said.
“But we see that these infrastructure objects (are) starting to be targeted specifically.”
Mr Prystaiko said Putin was facing a "lack of progress", with civilians meeting his tanks with "Molotov cocktails from their cars" rather than the "flowers" he dreamed of.
"The support and resilience is going so much against his plans and in Russia themselves start asking questions, 'What are we doing?'," the ambassador said.
"I believe they might … try to block our cities, try to soften political position, try and maybe ... some riots in Ukraine, because of the lack of food, against the Government."
Asked how Ukrainian forces were coping as they battled invaders, Mr Prystaiko said: “Our armed forces are trying their best.
“People are signing up for territorial defence and for reserves.”
“We have plus 100,000 people in forces. We have some issues with equipping them and arming them, but this is just logistical, we will cover it.”
He also accused Moscow of plundering Ukrainian water to supply Crimea, which Moscow annexed in 2014.
“They have already started stealing water from the major rivers,” he said.
“They blew up a dam which was covering a canal from a neighbouring area to Crimea.”
Despite Kremlin soldiers again assaulting sovereign territory, Ukrainian medics were treating wounded Russian troops, he said.
“We have found the softness in our hearts to treat Russians (who are) wounded and we are keeping them and we promised everybody they will be treated in our hospitals along with our own people and then be returned to Russia after war is over,” said Mr Prystaiko.
Dr Artis Pabriks, Latvia's Deputy PM and Defence Minister, confirmed to MPs that Belarusian troops had entered Ukraine.
“This basically means we have two aggressives at the moment officially,” he said.
He warned that Putin would use any means against the Ukrainian people.
“I am very much concerned that Russian troops, following orders from the top, will go into the mode similar to that President [Bashar al-] Assad was using against his population," he said.
Lithuanian Foreign Minister Gabrielius Landsbergis said it was clear that Putin has "no boundaries" to what instruments he will use against Ukraine.
"It is possible that this war will become a massacre," he told MPs.
Meanwhile, Boris Johnson warned “Putin will continue to tighten the vice” on Ukraine as he travelled out to the region for crisis talks.
The Prime Minister arrived in Poland where he warned the Russian war in Ukraine "is worse than our predictions", "we’re seeing an unfolding disaster in our European continent."
Standing beside Poland’s Prime Minister Mateusz Morawiecki, he said: " Vladimir Putin is prepared to use barbaric and indiscriminate tactics against innocent civilians.
"To bomb tower blocks, to send missiles into tower blocks, to kill children, as we are seeing in increasing numbers".
But in a speech in Warsaw, he said Vladimir Putin had made a "colossal mistake" by invading Ukraine.
"Putin has lied to his people and to his troops about how this conflict would go, and he has now been caught out in that lie," he said.
"They have not been welcomed to Ukraine as he prophesised, their tanks have not been cheered in the streets or garlanded with flowers.
"Instead, Ukrainians have mounted an astonishing and tenacious resistance."
