Russian forces have massed at the border with Ukraine and intense diplomatic activity has failed to ease tensions.
The Foreign Office said: “Some embassy staff and dependants are being withdrawn from Kyiv in response to the growing threat from Russia.
“The British Embassy remains open and will continue to carry out essential work.”
Meanwhile, Nato committed more ships and fighter jets to eastern Europe.
Denmark is sending a frigate to the Baltic Sea and is set to deploy F-16 fighter jets to Lithuania, Spain is sending ships and is considering sending fighter jets to Bulgaria, France has expressed its readiness to send troops to Romania, and the Netherlands is sending two F-35 fighter planes to Bulgaria from April.
The UK believes there is a significant risk that Russian president Vladimir Putin will launch a full-scale invasion of Ukraine.
Foreign Secretary Liz Truss has accused the president of plotting to install a pro-Moscow leader as head of the Ukrainian government.
The Foreign Office took the unusual step of naming former Ukrainian MP Yevhen Murayev as a potential Kremlin candidate to take over in Kyiv – a claim dismissed as provocative “nonsense” by Moscow.
Deputy Prime Minister Dominic Raab warned on Sunday there was a “very significant risk” of a Russian invasion of its neighbour.
“The world needs to keep its eye on this and be very clear with President Putin that it would not do this cost-free, that there would be a price,” he told the BBC.
“A price in terms of the strenuous defence that we would expect the Ukrainians to put up, but also the economic cost through sanctions, which are of course more effective if the international community speaks as one or at least with a broad consensus.”
There are concerns that the crisis could trigger a spike in European energy prices, with The Times reporting that officials fear Russia could restrict supplies of gas in response to sanctions.
Register for free to continue reading
Registration is a free and easy way to support our truly independent journalism
By registering, you will also enjoy limited access to Premium articles, exclusive newsletters, commenting, and virtual events with our leading journalists
Already have an account? sign in