In one 2018 cable published by the Mail on Sunday, U.K. ambassador Kim Darroch says President Donald Trump pulled out of an global nuclear deal with Iran as an act of "diplomatic vandalism" to spite his predecessor, Barack Obama.
It followed the announcement Mr Darroch had made a decision to quit, saying his position had become "impossible" following the publication of cables in which he described the Trump administration as "inept" and "dysfunctional".
Darroch was reported to have described the White House as "inept", prompting Trump to claim the ambassador was a "pompous fool" whom he would no longer deal with.
In an apparent backtrack on Friday, the US President said he wished the British ambassador well and that he had been told Darroch had actually said "some very good things" about him.
Separately, the Sunday Times reported that a government investigation had identified a civil servant as the person responsible for the leak.
Scotland Yard performed a climbdown on Saturday following accusations it had attempted to use the furore over the leaking of comments by the British ambassador about President Trump to silence the British media. Darroch has since resigned, saying it was "impossible" for him to continue. The perpetrator should face the consequences of their actions. Darroch also criticized the Trump administration's strategy concerning the withdrawal.More news: Beth Chapman Eulogized by Shannon Tweed, Co-Stars During Funeral
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In a statement, the London Metropolitan police's assistant commissioner, Neil Basu, said that "given the widely reported consequences of that leak", there had been "damage caused to United Kingdom worldwide relations" and that there "would be clear public interest in bringing the person or people responsible to justice".
London's Metropolitan Police sparked widespread condemnation on Saturday after warning journalists that publishing leaked documents could be a criminal matter.
"Also, to anyone who knows or suspects those responsible, or who has any information, please come forward", Basu said, assuring the "strictest confidence" to anyone who did get in contact with information.
Former Foreign Secretary Boris Johnson said: "It can not be conceivably right that newspapers or any other media organisation publishing such material should face prosecution".
The former defence secretary Sir Michael Fallon, however, prompted outrage after he told the Today programme that journalists should be subject to the Official Secrets Act.
Britain's most senior counter-terrorism police officer had warned the media not to print any more leaked documents, saying it could breach the Official Secrets Act.
Johnson backed those concerns, telling a Tory hustings event in Bedfordshire that any such prosecution would amount to an "infringement of press freedom" and have a "chilling effect" on public debate.