LONDON (Reuters) - U.S. President Donald Trump lashed out at “foolish” British Prime Minister Theresa May and her “wacky” Washington ambassador on Tuesday, stepping up a tirade against a close ally whose envoy had branded his administration inept.

FILE PHOTO - Britain's Prime Minister Theresa May and U.S. President Donald Trump attend a joint news conference at the Foreign & Commonwealth Office, in London, Britain June 4, 2019. Stefan Rousseau/Pool via REUTERS

May has given her full support to Kim Darroch after he described Trump’s administration as “dysfunctional” and “inept” in memos that were leaked to a British newspaper on Sunday.

While ministers and May’s spokesman have stated the leaked cables were only a partial reflection of Darroch’s assessments and did not reflect the government’s views, they have infuriated Trump, who fired off a second series of scathing tweets.

“The wacky Ambassador that the UK foisted upon the United States is not someone we are thrilled with, a very stupid guy,” Trump wrote, describing Darroch as a “pompous fool”.

“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. I told @theresa_may how to do that deal, but she went her own foolish way - was unable to get it done. A disaster!”

May is due to leave office this month and the spat with the United States divided the two contenders who are battling to replace her.

Boris Johnson, the former London mayor and favorite to enter Downing Street as the next prime minister, said Britain’s relationship with the United States was incredibly important.

Asked in a television debate whether Darroch would retain his job under a Johnson government, he said he would not be so presumptuous as to think he would be in a position to take that decision.

He then said it was not “necessarily” the right thing for Trump to have said, but added: “Let’s face it, our relationship with the U.S. is of fantastic importance.”

Foreign Secretary Jeremy Hunt went much further, saying the comments were “disrespectful and wrong” to May and the country.

“You said the UK/US alliance was the greatest in history and I agree,” he said on Twitter. “But allies need to treat each other with respect as @theresa_may has always done with you. Ambassadors are appointed by the UK government and if I become PM our Ambassador stays.”

The timing of the discord comes as Britain is hoping to strike a major trade deal with its closest ally after it leaves the European Union, an exit scheduled for Oct. 31.

Both Johnson and Hunt have indicated they could support leaving the bloc without a deal, making a future agreement with the United States even more important.

Britain’s trade minister Liam Fox said he would apologize to Trump’s daughter Ivanka whom he met during a visit to Washington.

On Monday, Trump had tweeted that he would sever ties with the diplomat and that it was “good news” that Britain would soon have a new prime minister.

“SERIOUS CONSEQUENCES” FOR LEAKER

Before Trump’s latest broadside, May’s spokesman said Darroch would stay in place and that envoys had to feel confident they could share their frank assessments.

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“She (May) said we had made clear to the U.S. how unfortunate this leak is, and that the extracts were selective and do not reflect the closeness of our relationship,” the spokesman said.

In his confidential memos dating from 2017 to the present, Darroch had said reports of in-fighting in the White House were “mostly true” and last month described confusion within the administration over Trump’s decision to call off a military strike on Iran.

“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,” Darroch wrote in one cable.

British officials have launched an inquiry to find out who was responsible for the leak.

Christopher Meyer, a former British ambassador to Washington, said there was a “possible range of villains”.

“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,” he told BBC radio.