Video report by ITV News Correspondent Rebecca Barry
Donald Trump has hit back at the UK's ambassador to the US after a leaked memo revealed he described the US President's White House as “uniquely dysfunctional” and “inept”.
The Foreign Office is investigating a leak of memos that detail Sir Kim Darroch’s assessments of the Trump administration from 2017 to the present.
Officials insisted the relationship with the White House could withstand the “mischievous behaviour” of the leak and defended Sir Kim’s candid style.
Reacting to the leaked comments, President Trump said: "The ambassador has not served the UK well, I can tell you that.
"We are not big fans of that man and he has not served the UK well. So I can understand it, and I can say things about him but I won't bother."
A formal leak investigation will now be launched, a spokesperson for the Foreign Office has confirmed.
Foreign Secretary Jeremy Hunt said he was very concerned about diplomatic memos being leaked to the Mail on Sunday and there would be serious consequences for the person behind the leak.
Tom Tugendhat, chair of the Commons Foreign Affairs Committee, said he hopes there are arrests and prosecutions following a "rigorous" inquiry.
He said: "The leaks themselves aren't particularly damaging, what is damaging is the fact that the UK seems at the moment to be incapable of stopping several leaks.
"There was the leak from the National Security Council about Huawei and now this package of information.
"And it shows that there is somebody or perhaps some people in the UK administration who are, frankly, reckless and incredibly stupid and putting at risk the interests and, in some cases, more than that of British people around the world."
He said there is a need for a rigorous inquiry conducted by police and he added: " I would hope arrests and prosecutions to follow."
Foreign Secretary Jeremy Hunt has sought to downplay the "disappointing" leak, saying they were the "personal views" of Sir Kim and did not reflect his own, or the Foreign Office's.
"Obviously it's very disappointing that this correspondence has come out into the open," Mr Hunt said.
"But it's also important to say that it's the job of ambassadors to give frank, personal opinions about what's happening in the countries they serve in and those are just that: personal opinions.
"They're not the opinions of the British Government or my opinion either.
"We continue to think that under President Trump the US administration is not just highly effective, but the best possible friend for Britain on the international stage."
The diplomatic memos, obtained by the Mail on Sunday, suggest that in order to communicate with the president “you need to make your points simple, even blunt”.
In the cache of documents, Sir Kim gives a scathing assessment of the White House: “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.”
He questioned whether the White House “will ever look competent”.
Following Mr Trump’s state visit to the UK in June, Sir Kim warned that although the president had been “dazzled” by the pomp and ceremony of the trip, his administration would remain self-interested and “this is still the land of America First”.
In one of the most recent documents, Sir Kim refers to “incoherent, chaotic” US policy on Iran and questions Mr Trump’s publicly stated reason for calling off a retaliatory air strike against Tehran following the downing of an American drone.
The US and Iran have been at the brink of armed conflict over tensions in the Gulf, and Mr Trump stated that he called off a planned air strike with minutes to spare because of the potentially high number of casualties.
But Sir Kim said that the explanation “doesn’t stand up”, and suggested it may have been motivated by Mr Trump’s focus on the 2020 re-election campaign and his previous promises not to involve the US in foreign conflicts.
“It’s more likely that he was never fully on board and that he was worried about how this apparent reversal of his 2016 campaign promises would look come 2020,” Sir Kim said.
He said it was “unlikely that US policy on Iran is going to become more coherent any time soon” as “this is a divided administration”.
In a particularly sensitive leak, a 2017 letter to the National Security Adviser Sir Mark Sedwill – sent 150 days into the Trump administration – laid bare the trouble in the White House.
Media reports of “vicious infighting and chaos” were “mostly true” despite the president’s attempts to brush them off.
Referring to the early allegations of collusion between the Trump campaign and Russia, the memo said “the worst cannot be ruled out”.
A lengthy investigation by Robert Mueller published earlier this year cleared the Trump team of the collusion allegations.
A Foreign Office spokesman said: “The British public would expect our ambassadors to provide ministers with an honest, unvarnished assessment of the politics in their country.
“Their views are not necessarily the views of ministers or indeed the Government.
“But we pay them to be candid. Just as the US ambassador here will send back his reading of Westminster politics and personalities.
“Of course we would expect such advice to be handled by ministers and civil servants in the right way, and it’s important that our ambassadors can offer their advice and for it remain confidential.
“Our team in Washington have strong relations with the White House and no doubt… these will withstand such mischievous behaviour.”