The UK has temporarily withdrawn staff from its embassy in Tehran, as tensions between the US and Iran prompt warnings from a number of countries to their citizens in the Middle East.
In a statement, the UK Foreign Office said its embassy in Iran's capital would continue to operate remotely.
Meanwhile, the US embassy in Israel told some non-emergency staff that they could leave the country on Friday. US Ambassador to Israel Mike Huckabee advised staff who wished to leave to "do so TODAY", the New York Times reported.
It comes a day after Washington and Tehran held talks widely seen as a last ditch effort to avoid a war over Iran's nuclear ambitions.
A number of other countries including China, India and Canada have told their citizens to leave Iran as soon as possible due to the prospect of hostilities.
He has ordered the largest US military build-up in the Middle East since the US-led invasion of Iraq in 2003, while Iran has vowed to respond to an attack with force.
Vice-President JD Vance told the Washington Post that strikes remain under consideration, but there was "no chance" of the US becoming involved in a drawn-out war.
Thursday's indirect talks in Geneva between the two countries resulted in "significant progress", mediator Oman said, adding that further negotiations would take place soon.
There has been no official response from the US, while Tehran hailed "good progress".
