Video report by ITV News Washington Correspondent Robert Moore
Donald Trump's was "disrespectful and wrong" when he called Theresa May "foolish" and the UK's ambassador to the US "a very stupid guy", Jeremy Hunt has said.
The Foreign Secretary hit back at the US President after he dramatically stepped up the war of words over Britain’s US ambassador, Sir Kim Darroch, branding him a “pompous fool”, and said the Prime Minister was "foolish" not to listen to him over Brexit.
In two tweets, the Tory leadership hopeful wrote to Mr Trump: "Friends speak frankly so I will: these comments are disrespectful and wrong to our Prime Minister and my country.
"Your diplomats give their private opinions to @SecPompeo and so do ours!
"You said the UK/US alliance was the greatest in history and I agree...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 issue was discussed during the ITV Tory leadership debate between Mr Hunt and his rival Boris Johnson, with the former echoing his earlier remarks.
The Foreign Secretary stood by his previous comments that the Government backs Sir Kim, and expects its ambassadors to offer frank assessments of the countries they are in.
He added that if he became prime minister he could "certainly keep him (Sir Kim) until he is due to retire" at the end of 2019.
Suggesting that Mr Trump had no right to be telling the UK who should be its ambassador, Mr Hunt said it was a "matter for the United Kingdom".
Unlike Mr Hunt, Mr Johnson refused to say whether he would keep Sir Kim in post if he were to be prime minister, adding that whoever had leaked the documents "deserves to be eviscerated".
Earlier on Tuesday, the US President wrote: "The wacky Ambassador that the UK 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.
"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."
Mr Trump's tweets followed a series of others put out on Monday night in which he again lambasted Mrs May over her handling of Brexit, and slammed Sir Kim.
The US President's attacks come after leaked memos revealed that Sir Kim had described the Trump administration as "inept", "incompetent" and "uniquely dysfunctional" in leaked Foreign Office memos dating from 2017 to the present.
Despite Mr Trump insisting that "we will no longer deal" with Sir Kim, the UK Government has given him its full support, saying that ambassador's are employed to give frank assessments of the countries they are in, but making clear the views are the 65-year-old's personal ones, and do not reflect the outlook of Mrs May or her team.
A Government spokesperson said ambassadors should be able to provide "honest, unvarnished assessments of the politics in their country".
“Sir Kim Darroch continues to have the Prime Minister’s full support...
“The UK has a special and enduring relationship with the US based on our long history and commitment to shared values and that will continue to be the case.”
The Foreign Office said it is investigating the leak that detail Sir Kim's assessments of the Trump administration from 2017 to the present.
If criminality is found, police could become involved.
Sir Kim has been the UK's ambassador to the US since January 2016, before taking the role he served as national security adviser to former prime minister David Cameron.
He is due to stand down, regardless of recent events, at the end of 2019.
Sir Kim's career spans three decades and he joined the diplomatic service in 1977, after graduating from Durham University with a degree in zoology.
Do we know who leaked the information?
It is not known who leaked the information, but Political Correspondent Paul Brand said that the material came from both diplomatic telegrams and letters, meaning that it came from a senior source.
Brand explained that while up to 1,000 people can have access to a diplomatic telegram, letters are sent to around only 10 senior figures.
He added that both letters and telegrams are automatically deleted after three months, meaning the person behind the leaks had been purposefully saving them.
Brand continued that searches of computer and printer history may enable the source of the leak to be traced.