The UK has begun to withdraw staff from the British embassy in Ukraine amid warnings of a Russian invasion.

Officials say there have been no specific threats to British diplomats, but about half of the staff working in Kyiv will return to the UK.

The US is taking similar action, saying a Russian invasion could come “at any time”, but EU staff will stay in place.

Russia has denied plans for military action, but tens of thousands of troops have amassed on the border.

The embassy moves seem to be precautionary, and nothing specific is thought to have occurred in the past 24 hours to have triggered the decisions of the US and UK.

The US state department also warned people not to travel to Ukraine and Russia due to the ongoing tension and “potential for harassment against US citizens”.

Ukraine said it was “premature” of the US to withdraw staff and “a display of excessive caution”.

EU foreign policy chief Josep Borrell said he would not “dramatise” the tensions by withdrawing staff.

“We are not going to do the same thing because we don’t know any specific reasons,” he said as he arrived for a meeting with foreign ministers.

The head of Nato has warned there is a risk of fresh conflict in Europe, with an estimated 100,000 Russian troops now at the border with Ukraine, and diplomatic efforts have failed to ease tensions.