Some British embassy staff and their dependants are being pulled out of Kyiv in response to the mounting Russian threat to Ukraine.
The Foreign Office confirmed the move after the United States ordered the families of all American personnel at the US Embassy to leave the country in response the the risk of an invasion.
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The Foreign Office said: "Some embassy staff and dependants are being withdrawn from Kyiv in response to the growing threat from Russia.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."
Sources at the Foreign Office told the BBC the move was not the result of any specific intelligence targeting British diplomats, but a response to the growing risk of a Russian incursion and the potential risk to UK officials in the Ukraine.
The UK believes there is a significant risk that Russian president Vladimir Putin will launch a full-scale invasion of Ukraine.
Tensions in Ukraine have been increasing for months after the Kremlin massed some 100,000 troops near Ukraine's borders, a dramatic buildup the West says is preparation for a war to prevent Ukraine from ever joining the NATO security alliance.
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."
The European Union does not plan to withdraw diplomats' families from Ukraine at the moment, EU foreign policy chief Josep Borrell said on Monday after Washington announced such a move, pointing out a military attack by Russia could come at any time.
The U.S. State Department announced on Sunday it was ordering diplomats' family members to leave Ukraine, in one of the clearest signs yet that American officials are bracing for an aggressive Russian move in the region.
"We are not going to do the same thing because we don't know any specific reasons. But (US) Secretary (of State Antony) Blinken will inform us," Borrell told reporters as he arrived for a meeting with his EU counterparts that Blinken is expected to join online at around 2pm.
The Kremlin has repeatedly denied planning to invade, but the Russian military already took a chunk of Ukrainian territory when it seized Crimea and backed separatist forces who took control of large parts of eastern Ukraine eight years ago.
"Negotiations are going on", Borrell said, adding he saw no reason to leave Ukraine "unless Secretary Blinken gives us an information that justifies a move".
The EU's foreign ministers are expected to issue a warning to Russia over its troop buildup at Ukraine's border.
On Sunday night, the US State Department ordered the evacuation of diplomats’ family members from Kyiv as non-essential staff were also given the option of leaving, write David Millward and Marcus Parekh.
It also advised US citizens to consider departing.
“There are reports Russia is planning significant military action against Ukraine,” the State Department said in a statement.
“The security conditions, particularly along Ukraine’s borders, in Russia-occupied Crimea, and in Russia-controlled eastern Ukraine, are unpredictable and can deteriorate with little notice.”
The announcement comes as the New York Times reports that Joe Biden is considering deploying several thousand troops along with warships and aircraft to the Baltic region and Eastern Europe.
Mr Biden, who has been reluctant to increase the US’s military involvement, reportedly discussed an array of options with senior Pentagon officials at Camp David on Saturday.
Proposals included sending up to 5,000 troops to eastern European allies, with the option of increasing the tenfold if the situation worsens.
However, the US is understood to have ruled out deploying troops in Ukraine itself, although officials have floated plans to throw its weight behind an insurgency should the Russians invade.
As Britain followed America's lead in evacuating embassy staff, EU diplomats announced their staff would remain in the country.
Ukrainian officials said it was "premature" of the United States to evacuate the families of its diplomatic staff.
"We consider such a step by the American side premature and a display of excessive caution," Ukrainian foreign ministry spokesman Oleg Nikolenko said in a statement.
The move had been signalled by US Secretary of State Antony Blinken earlier on Sunday when he appeared on NBC’s Meet the Press.
“I have no higher responsibility than the safety and well-being of the folks who work for the State Department and who are under my care, in a sense,” he said.
“So we're tracking this very, very closely. We're looking at it on really a daily basis.”
“And if we need to make a determination that we should draw down some of the folks at the embassy, we'll do that based on the security need.” he added.
Washington has also issued a travel advisory warning Americans to avoid all travel to Russia due to the situation "along the border with Ukraine" warning they could face "harassment".
Last week White House press secretary, Jen Psaki, warned that Russia could invade Ukraine at any time.
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