LONDON — Days after diplomatic cables that blasted President Donald Trump's administration as "inept," Britain's ambassador to the U.S. Kim Darroch has resigned, according to the U.K. Foreign Office.

  • UK prime minister called Kim Darroch's resignation 'matter of regret'
  • Leaked cables claim that Trump's economic plans could wreck world trade
  • President Donald Trump lashed out on Twitter

Darroch said in a letter Wednesday that even though his posting was due to end this year, he believed "in the current circumstances the responsible course is to allow the appointment of a new ambassador."

Darroch said he is "grateful to all those in the UK and the US, who have offered their support during this difficult few days."

Prime Minister Theresa May said it was a "matter of regret" that Darroch resigned.

Darroch's forthright, unfiltered views on the U.S. administration — meant for a limited audience and discreet review — appeared in leaked diplomatic documents that were published in Britain's Mail on Sunday newspaper.

"Sir Kim Darroch, one of Britain's top diplomats, used secret cables and briefing notes to impugn Trump's character, warning London that the White House was 'uniquely dysfunctional' and that the President's career could end in 'disgrace,'" the newspaper reported. 

On Tuesday, Trump tweeted out his displeasure with Darroch.

The Associated Press contributed to this story.