President Trump has ripped into UK Prime Minister Theresa May and ambassador to the US, Sir Kim Darroch, following a series of leaked emails that have threatened to blow up the "special relationship."

"The wacky Ambassador that the U.K. foisted upon the United States is not someone we are thrilled with, a very stupid guy. He should speak to his country, and Prime Minister May, about their failed Brexit negotiation, and not be upset with my criticism of how badly it was handled," the US leader tweeted on Tuesday.

"I told @theresa_may how to do that deal, but she went her own foolish way-was unable to get it done. A disaster! I don't know the Ambassador but have been told he is a pompous fool. Tell him the USA now has the best Economy & Military anywhere in the World, by far … … and they are both only getting bigger, better and stronger.....Thank you, Mr. President!"

The extraordinary spray comes after a Downing Street spokesman described leaked diplomatic emails written by the US ambassador to the UK as "unfortunate" but insisted the US and UK had a "special and enduring relationship".

Advertisement

"We have made clear to the US how unfortunate this leak is. The selective extracts leaked do not reflect the closeness of, and the esteem in which we hold, the relationship," the spokesman said.

Emails written by Sir Kim were leaked to the Mail on Sunday and showed him describing the Trump White House as "inept," "insecure" and "incompetent". They outlined his fears the US President would attack Iran, how officials had to "flood the zone" with information to get a message through to Trump, and warned he could get another four years in office at the 2020 election.

"We don't really believe this Administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept," Sir Kim reportedly wrote.

He said the US leader "radiates insecurity" and his team were "dazzled" by the state visit to the UK in which President Trump's four adult children joined him at a state banquet at Buckingham Palace.

The leaked emails from the ambassador said President Trump
The leaked emails from the ambassador said President Trump "radiates insecurity" and his team were "dazzled" by the state visit to the UK. Photo / AP

"His team were also dazzled, telling us that this had been a visit like no other — the hottest ticket of their careers. These are close contacts, with whom we have spent years building relationships: they are the gate keepers and the "Trump Whisperers" — the individuals we rely upon to ensure the UK voice is being heard in the West Wing," he said.

The leak drew the ire of President Trump, who fired off a series of critical tweets on Monday calling Theresa May's Brexit deal a "mess" and vowing not to work with Sir Kim.

"I have been very critical about the way the UK and Prime Minister Theresa May handled Brexit. What a mess she and her representatives have created," he said.

"I told her how it should be done, but she decided to go another way. I do not know the Ambassador, but he is not liked or well thought of in the US. We will no longer deal with him. The good news for the wonderful United Kingdom is that they will soon have a new Prime Minister. While I thoroughly enjoyed the magnificent State Visit last month, it was the Queen who I was most impressed with!"

Advertisement

Sir Kim was also uninvited to a White House dinner as a result.

The diplomatic bust up is the latest in a rocky relationship between the key allies since President Trump took office. The US leader has veered off script by holding forth on who should be the next UK Prime Minister and suggesting how Theresa May should conduct Brexit negotiations.

It has also raised questions over how sensitive information found its way to the media. Critics say it makes Sir Kim's role untenable, however Conservatives have backed the ambassador, saying he needs to be able to provide honest advice to UK leaders.

Former Foreign Secretary William Hague told the BBC the government was right to back Sir Kim.

President Donald Trump reiterated his feeling that outgoing British Prime Minister Theresa May handled Brexit poorly. Photo / AP
President Donald Trump reiterated his feeling that outgoing British Prime Minister Theresa May handled Brexit poorly. Photo / AP

"You can't change an ambassador at the demand of a host country," he said. "It is their job to give an honest assessment of what is happening in that country."

Others have questioned the source of the leak, with ex-British ambassador and a close friend of Sir Kim's telling the BBC there was a "possible range of villains" who may have been behind it.

"It was clearly somebody who set out deliberately to sabotage Sir Kim's ambassadorship, to make his position untenable and to have him replaced by somebody more congenial to the leaker."

Trump has previously suggested Nigel Farage would make a good ambassador to the US, however Farage sidestepped this on Monday, saying he was "not a diplomat".

The Conservative Party is currently holding a leadership race between Jeremy Hunt and Boris Johnson for who will become the next UK Prime Minister.