MPs looking into the leaking of US ambassador’s cables also criticise FCO and Boris Johnson

Civil servants who leak sensitive diplomatic cables should face losing their pension as well as more serious charges under the Official Secrets Act, according to a foreign affairs committee report.

The report, which examines the leaking of cables sent by Sir Kim Darroch while he was UK ambassador to the US, calls for a zero-tolerance approach to what it describes as “the canker of leaks”.

Transatlantic relations were thrown into crisis by the leak of the confidential cables, sent to the Foreign Office, in which Darroch described a dysfunctional White House under Donald Trump.

The leak was passed on to the Mail on Sunday by Steven Edginton, a Brexit party activist. The leaker has not yet been identified by a police investigation.

Through allies, Darroch indicated he resigned as ambassador, in part, owing to the lack of support from the incoming prime minister, Boris Johnson.

The foreign affairs select committee said on Thursday: “Those who leak are reckless and dangerous and the government should never tolerate such actions.

“It would be wholly disingenuous to suggest that this is the altruistic work of a whistleblower. The culprit (or culprits) has done significant harm to British interests abroad and should feel the full force of the law.”

The committee highlighted the failure of the Foreign Office to investigate thoroughly a 2016 leak to the Sunday Times of a confidential paper (£) that revealed how Darroch was courting the incoming Trump administration.

The Foreign Office (FCO) could not adopt double standards towards leaks by only investigating those that did not show the department in a favourable light, said the committee.

Otherwise, a culture of leaks would emerge that would make it impossible for diplomats to do their job because they would be unable to give candid accounts of events in the country about which they were reporting.

It added: “The FCO – and government more widely – must not pick and choose with leaks: if it sends out a message that some leaks can be tolerated, it helps create a culture where those who are tempted to leak are emboldened to do so.”

Although the committee heard from Darroch’s predecessors that confidentiality ultimately relies on the human factor, it recommend the Foreign Office revise circulation lists for some cables, as well as the ability of those in receipt to be able to forward them to others.

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It said civil servants found guilty of leaking should face the risk of loss of employment rights, including pensions, as well possible claims for damages. It also said the possible charges under the Official Secrets Act should be reviewed.

In an implicit criticism of Johnson, the committee said Darroch should have been defended by politicians completely. Johnson, a former foreign secretary, initially refused to say Darroch should stay on as ambassador in part because of the anger of Donald Trump over the diplomat’s remarks.

It said: “Civil servants must feel confident that they have the complete backing of those they serve when undertaking the often complex and sensitive tasks that allow government to function effectively. This recent leak has resulted, according to the former foreign secretary Lord Hague, in ‘making an ambassador’s position untenable’.”

In remarks aimed at Johnson, William Hague told the committee a “dangerous precedent” would be set by “a former foreign secretary appearing not to have backed the ambassador” .