SCOTLAND Yard has been called on to investigate the leak of sensitive diplomatic emails in which Sir Kim Darroch, Britain’s ambassador to the US, was revealed as branding the Trump administration “inept”.

During an Urgent Question in the Commons, Conservative backbencher Tom Tugendhat, who chairs the Foreign Affairs Committee, told MPs he had written to Cressida Dick, the Metropolitan Police Commissioner, to "ask that a criminal investigation also be opened into the leak". A Cabinet Office probe has already been launched.

The Kent MP said: “I fear that we are developing a culture of leaks and that will be extremely detrimental to the UK because leaks damage our reputation, have an impact on our ability to function effectively and undermine our relationships with our allies.”

He told MPs: “Whichever parts of the Government can help to look into the source of this leak, including the security services, should be asked to assist with the matter urgently, and that any actions short of these steps will send out a dangerous message that the UK is reckless with information and cavalier with the trust placed in it?”

Sir Alan Duncan, the Foreign Office Minister, said he shared his colleague’s concern about “this unacceptable leak” and sought to reassure him that the Government was treating it with the “seriousness it deserves”.

Insisting the investigation would be “comprehensive,” he added: “If evidence of criminality is found, then yes, the police could be involved. The most important focus is to establish who is responsible for this despicable leak.”

Emily Thornberry for Labour insisted that Sir Kim had been “betrayed”. She told MPs: “He has been hung out to dry even though his only crime was to tell the truth. He told the truth about Donald Trump and that was because it was his job.”

The Shadow Foreign Secretary urged the Government to commit to reassuring all of Britain’s diplomats abroad that “when they feed back their reports they do not need to fear politically motivated leaks and they can, as, for the good of our country, they must, keep telling the truth”.

Stephen Gethins for the SNP insisted officials had to be able to approach ministers openly “without fear or favour,” and told Sir Alan: “There are members in his own party for whom everyone else is collateral in this Brexit mess and the damaging infighting it has caused, which has nothing to do with the best interests of the citizens they are supposed to serve.”

But the minister replied: “This is not about Brexit. This is about an utterly disgraceful leak and whoever is responsible needs to be traced and punished.”

Earlier, Downing St made clear Theresa May continued to have “full faith” in Sir Kim and stressed: “Our ambassadors provide honest, unvarnished assessments of politics in their country. Those views are not necessarily the views of ministers or indeed the Government.”

The ambassador’s leaked emails date from 2017 to the present day. In them, he said: "We don't really believe this administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction-riven; less diplomatically clumsy and inept."

Jeremy Hunt, the Foreign Secretary, made clear he did not agree with all the views expressed by Sir Kim in the leaked messages as he insisted Britain had the "warmest" of relationships with America.