A police investigation into the leak of memos written by the UK ambassador to the US has been criticised by former chancellor George Osborne for "encroaching on press freedom".
Kim Darroch's emails, in which he said Donald Trump was "inept", were released to the Mail on Sunday last weekend and eventually led to the ambassador's resignation.
The inquiry by the Metropolitan Police Counter Terrorism Command, which is responsible for investigating allegations of criminal breaches of the Official Secrets Act, was announced in a statement on Friday attributed to assistant commissioner Neil Basu.
Mr Basu said: "Given the widely reported consequences of that leak I am satisfied that there has been damage caused to UK international relations, and there would be clear public interest in bringing the person or people responsible to justice.
"The investigation will be reviewed at every stage to ensure a proportionate investigation is undertaken.
He asked the person behind the leaks to turn themselves in and avoid wasting detectives' time, saying: "You can stop this now. Turn yourself in at the earliest opportunity, explain yourself and face the consequences."