In a cable sent afterwards, Darroch reportedly indicated there were divisions in Trump's team over the decision, and criticised the White House for a lack of long-term strategy.
"The publication of these specific documents, now knowing they may be a breach of the OSA, could also constitute a criminal offence and one that carries no public interest defence", said Neil Basu, who heads the investigation as chief of counter-terrorism unit.
Announcing the criminal investigation on Friday, the Met's Assistant Commissioner Neil Basu said the alleged leak had damaged United Kingdom global relations, reports the BBC. However, you are now also responsible for diverting busy detectives from undertaking their core mission.
On Friday, President Trump said he wished the susceptible ambassador correctly and that he had been instructed Sir Kim had if fact be told said "some very magnificent issues" about him. You can stop this now.
"I would advise all owners, editors and publishers of social and mainstream media not to publish leaked government documents that may already be in their possession, or which may be offered to them, and to turn them over to the police or give them back to their rightful owner, Her Majesty's Government", Basu said.More news: Sudanese protesters demand justice for army crackdown victims
In a tweet on Wednesday, the U.S. president also accused Iran of "secretly" enriching uranium, in violation of the 2015 Iranian nuclear deal that the USA pulled out of past year.
The leak, published in the Daily Mail, suggested that the envoy branded US President Donald Trump as "inept and incompetent" and his administration "dysfunctional, unpredictable [and] diplomatically clumsy".
Johnson said Darroch had not watched the debate but had heard an inaccurate account of what was said.
"(Darroch) said that what somebody had relayed to him had certainly been a factor in his resignation", he told BBC television in a testy interview.
"I can not think of a worse example of a heavy-handed approach by the police to attempt to curtail the role of the media as a defence against the powerful and those in authority", said Ian Murray, Executive Director of the Society of Editors.More news: Police issue Amber Alert for 2 boys last seen with grandfather
"If I were the Metropolitan police commissioner, and I wanted to maintain my credibility and the credibility of my force, I would quickly distance myself from this very stupid and ill-advised statement from a junior officer who doesn't appear to understand much about press freedom", the former chancellor tweeted.
Boris Johnson, frontrunner in that race, has been heavily criticized by lawmakers in his own party and the opposition for failing to defend the ambassador.
The criticism led the Ambassador to step down on Wednesday, saying it was "impossible" for him to continue. Trump said his administration would no longer work with Darroch.
Johnson and Hunt are locked in a battle to succeed Theresa May, who resigned as prime minister after failing three times to get parliamentary approval for a withdrawal deal for Britain's exit from the European Union.
The new prime minister will be named on July 23 and take office the following day.More news: 'Star Trek' actress Stephanie Niznik dead at 52