London: The British Ambassador to the US, Sir Kim Darroch, has resigned following a diplomatic spat over a leaked email in which he criticised Donald Trump, the Foreign Office said.
Trump took aim at Darroch in a series of Twitter tirades over the last few days, calling him a "stupid guy" and a "pompous fool" after UK media published a confidential memo in which the British diplomat described the president's administration as "uniquely dysfunctional", the media reports said.
In a letter, Darroch wrote: "Since the leak of official documents from this embassy there has been a great deal of speculation surrounding my position and the duration of my remaining term as ambassador.
"I want to put an end to that speculation.
"The current situation is making it impossible for me to carry out my role as I would like."
He added: "Although my posting is not due to end until the end of this year, I believe in the current circumstances the responsible course is to allow the appointment of a new ambassador.
"I am grateful to all those in the UK and the US, who have offered their support during these difficult few days. "
Sir Simon McDonald, permanent under-secretary at the Foreign and Commonwealth Office, said he accepted Darroch's resignation with "deep personal regret".
He said the outgoing ambassador had behaved with dignity and professionalism over the last few days.
Speaking to MPs, the UK's outgoing Prime Minister Theresa May, also expressed her regret.
"Sir Kim has given a lifetime of service to the United Kingdom and we owe him an enormous debt of gratitude," she said.
Darroch's departure came not long after Boris Johnson, the former Foreign Secretary who looks most likely to take over from May in a Conservative Party leadership battle, fell short of offering the British ambassador his support during a televised debate with his fellow contender, current foreign secretary Jeremy Hunt.