Boris Johnson will visit Ukraine on Tuesday as fears increase over war with Russia.
The prime minister will be joined by foreign secretary Liz Truss on the trip, when he will also hold a press conference with Ukrainian president Volodymyr Zelensky.
Johnson is also due to speak to Russian president Vladimir Putin in a phone call on Monday afternoon as part of efforts to avoid a conflict in the region.
Russia has amassed tens of thousand of troops on the Ukrainian border.
Last week, Johnson warned Putin that any war with their neighbours would be “painful, violent and bloody”.
The prime minister’s trip to Ukraine will come amid the fallout from the Sue Gray report, which is being published this afternoon.
A spokesman for the PM said the UK was trying to persuade Russia not to launch a war with Ukraine.
He said: “As they face this Russian aggression, we on our part are seeking to reflect and shine a light on some of the approaches and tactics been used by Russia with the intention of encouraging them to step back from going any further.
“That’s what we’re seeking to do at all costs, but the prime minister will be speaking directly to President Zelensky tomorrow and I’m sure it will continue.”
Putin has been warned by the west that any military action against Ukraine will be met with economic sanctions.
The PM’s spokesman said: “I think that the Russians should be in no doubt that we have significant powers and we’ll take them further, which will place massive pressure on them should they continue on this path progression.”