HONG KONG (BLOOMBERG) - A diplomatic spat between the US and Britain over leaked diplomatic memos escalated after Donald Trump called the British ambassador in Washington a "stupid guy," and British. Foreign Secretary Jeremy Hunt accused the president of being "disrespectful."

"The wacky Ambassador that the UK foisted upon the United States is not someone we are thrilled with, a very stupid guy," Trump tweeted on Tuesday (July 9).

"I don't know the Ambassador but have been told he is a pompous fool."

The tweets followed a tirade late on Monday in which Trump froze out the envoy, Kim Darroch, saying the White House "will no longer deal with" him.

Trump also criticised Prime Minister Theresa May over her handling of Brexit.

"What a mess she and her representatives have created," he said.

Later on Tuesday, Hunt - who's vying with Boris Johnson to succeed May as premier - weighed in, tweeting that "allies need to treat each other with respect as @theresa-may has always done with you."

The row was triggered by the publication of diplomatic cables in the Mail on Sunday newspaper in which the ambassador called the US president "inept" and "incompetent."

That prompted the White House to cancel an invitation for Darroch to attend a dinner with Treasury Secretary Steven Mnuchin and the emir of Qatar, according to a US official.

May's office also said Darroch was not attending meetings Tuesday between Trade Secretary Liam Fox and US officials, though he was "supporting" the visit.

May had earlier sought to quell the rising tensions. Her spokesman, James Slack, told reporters in London the "selected" memos do not reflect the closeness and esteem with which Britain holds the relationship. He also said Darroch has the "full confidence" of the prime minister.

'Unvarnished Assessments'

The British. government was in contact with the US on both Monday and Tuesday, Slack said.

"We have also underlined the importance of ambassadors being able to provide honest, unvarnished assessments of the politics in their country," Slack told reporters.

Handling the fallout of a major diplomatic spat with Britain's most important foreign ally will be an early headache for either Johnson or Hunt, who will almost certainly face questions on the matter at a televised debate later on Tuesday.

"I've got a good relationship with the White House and I have no embarrassment in saying that," Johnson said in a pooled TV interview at a campaign visit in Manchester, northern England.

"It's very important we have a strong relationship with our most important ally. It is, has been, will be for the foreseeable future, our number one political, military, friend and partner."

Leak Probe

The Cabinet Office is leading a cross-government investigation into the leak of the memos, which were published in the Mail on Sunday newspaper and included Darroch calling Trump's White House "uniquely dysfunctional."

Hunt earlier acknowledged the possibility that the leak might be the result of a hack by a hostile government.

"Of course it would be massively concerning if it was the act of a foreign, hostile state," he told The Sun newspaper. "I've seen no evidence that that's the case, but we'll look at the leak inquiry very carefully."

Trump made a state visit to Britain last month and met with May, who will step down after failing to persuade Parliament to adopt her Brexit plan.

Darroch has been in his post since January 2016.

British ambassadorial postings can vary in length, but typically last four years, according to the Foreign Office, which declined to say when the envoy was due to leave Washington.

That timing suggests Darroch might be expected to leave his assignment early in 2020. If that happens, it would mean Johnson or Hunt would have to make a decision on a replacement within a few months of taking office.

Parliament's Foreign Affairs Committee announced on Tuesday that it will hold an urgent inquiry into "secure communications and the handling of classified information."