Defence secretary Ben Wallace has cut short a family holiday abroad in response to the “worsening” situation in Ukraine.
On Sunday the British government warned Russia could launch an invasion “very quickly”, possibly within days.
There are an estimated 130,000 Russian troops along Ukraine’s border but the Kremlin has insisted it is not planning an attack.
In a tweet on Sunday Morning, Wallace said: “Having returned from Moscow early on Saturday morning and because we are concerned about the worsening situation in Ukraine I have cancelled a planned long weekend abroad with my family and will be returning.”
Dominic Raab, the deputy prime minister, was heavily criticised for not returning to the UK from a family holiday sooner as the Taliban took control of Afghanistan in the summer.
Wallace has also compared diplomatic efforts to prevent an invasion to appeasement.
He said there was a “whiff of Munich in the air”, in a reference to the agreement that allowed German annexation of the Sudetenland in 1938 but failed to prevent the Second World War.
But Vadym Prystaiko, Ukraine’s ambassador to the UK, has said Wallace’s comparison was unhelpful.
He told the BBC Radio 4’s Broadcasting House programme: “It’s not the best time for us to offend our partners in the world, reminding them of this act which not bought peace but the opposite – it bought war.”
British nationals have been urged by the government to leave Ukraine as soon as possible.
They have been told not to expect a military operation to rescue them should they decide not to flee.
Speaking to the BBC’s Sunday Morning programme earlier, Northern Ireland secretary Brandon Lewis said it was “technically possible” an attack could come this week.
“If Russia does decide they want to move and they want to go and invade Ukraine they could do so very quickly,” he said.