THE US president is continuing his attack on the "wacky" UK ambassador, branding him "a very stupid guy" in a series of tweets.

It follows Donald Trump's vow to "no longer deal" with Kim Darroch after he branded the US president's administration "inept" in a leaked document.

Downing Street has said Theresa May has “full faith” in Darroch after the extraordinary breach of confidentiality triggered a political firestorm on both sides of the Atlantic.

Last night, Trump also criticised the Prime Minister for making a “mess” of Brexit, an attack he continued today.

"The wacky Ambassador that the UK foisted upon the United States is not someone we are thrilled with, a very stupid guy," he tweeted.

"He should speak to his country, and Prime Minister May, about their failed Brexit negotiation, and not be upset with my criticism of how badly it was handled.

"I told @theresa_may how to do that deal, but she went her own foolish way-was unable to get it done. A disaster! I don’t know the Ambassador but have been told he is a pompous fool.

He added: "Tell him the USA now has the best Economy & Military anywhere in the World, by far and they are both only getting bigger, better and stronger.....Thank you, Mr President!"

Conservative Tom Tugendhat, chairman of the Commons Foreign Affairs Committee, told MPs he had written to the Metropolitan Police Commissioner Cressida Dick to “ask that a criminal investigation also be opened into the leak”.

And Foreign Office minister Alan Duncan said police could be involved if evidence of wrongdoing over the leak is found, telling the Commons: “If evidence of criminality is found, then yes, the police could be involved.”