Trump memo: Investigation into leak looking at sources ‘inside and outside Whitehall’, warn officials

More than a hundred people who may have had access to Sir Kim Darroch’s emails across a number of Whitehall departments are part of the initial lines of inquiry

PM’s spokesperson says diplomat is a ‘dutiful, respected government official’ (PA)

The hunt to track down the source of the leak of confidential dispatches of Britain’s ambassador to Washington has turned into one of the most intense investigations of its kind in recent times, with a wide range of expertise available to the government being brought in to help.

The exact extent to which the security and intelligence services are involved at this stage cannot be disclosed.

But the issue is being treated with “the utmost importance” according to senior officials who say they are confident that “those who may be involved inside and outside Whitehall” in the affair will be tracked down.

Tom Tugendhat, the Conservative MP and chair of the Commons Foreign Affairs Committee, has written to the Scotland Yard commissioner, Cressida Dick, asking for an investigation to be carried out.

But, at the same time, other security agencies are also expected to play their part in the investigation.

More than a hundred people – who, depending on their security authorisation, may have had access to Sir Kim Darroch’s emails across a number of Whitehall departments – are part of the initial lines of inquiry.

At the same time the involvement of a foreign state has not been ruled out, and any previous actions by that state to carry out hybrid attacks in this country and attempts to manipulate domestic politics will be examined.

The Foreign Office is carrying out its own investigation, the findings of which will also be passed on to Sir Mark Sedwill, the cabinet secretary, head of the civil service, and national security adviser.

Telephones, laptops and other communications equipment of those who had access to Sir Kim’s confidential messages will be examined; that aspect of the inquiry as well as other ones are expected to involve the law enforcement agencies.

The controversy over the leaking of Sir Kim’s emails, which described the Trump administration as “ inept” and “dysfunctional” and warned that the president’s political career may end in disgrace, has turned into an extraordinary diplomatic crisis between two nations supposedly in a “special relationship”.

For the second day running Mr Trump took to Twitter to insult Sir Kim, a highly respected diplomat, as “very stupid”, “pompous” and “wacky”, having declared the previous day that his administration would no longer work with the him.

Trump also railed against Theresa May for being “foolish” in not listening to his advice about how to handle the Brexit negotiations.

A spokesperson for Ms May said that Sir Kim is “a dutiful, respected government official” and confirmed there are no plans for Ms May and Mr Trump to hold a call to discuss relations following the leak.

The concern over leaks and the mounting of the investigation, officials stress, is not confined to the ambassador’s messages but a whole series of unauthorised disclosures.

Gavin Williamson, the defence secretary, lost his job after allegedly leaking information about the proposed involvement of the Chinese telecommunications firm Huawei in the UK’s 5G network, and another investigation is under way into comments supposedly made by senior civil servants about the physical and mental condition of the leader of the opposition, Jeremy Corbyn.

Sir Simon McDonald, the permanent under secretary and head of the diplomatic service, will appear on Wednesday as the first witness in a newly launched inquiry by the Foreign Affairs Committee into the handling of classified information.

As well as the Scotland Yard commissioner, Mr Tugendhat had written to the prime minister and the foreign secretary calling for an immediate inquiry to identify the source of the leak and for criminal investigations by the Metropolitan Police. The letter to the foreign secretary lists a series of questions relating to a potential leak inquiry and general issues related to the handling of information by the Foreign Office.