NICOLA Sturgeon has hit back at the US president after his Twitter rant about the UK ambassador.

Donald Trump branded Kim Darroch the UK ambassador to the US “a very stupid guy” and vowed never to deal with him again.

The outburst follows on from an attack on Monday night which was prompted by a leaked document in which Darroch called the US president “inept”. Downing Street has said Theresa May has full faith in the ambassador.

Trump’s rant yesterday also took aim at the Prime Minister, saying she had made a “mess” of Brexit and should have followed his advice on the matter.

The First Minister intervened challenging the next PM to confront such behaviour by the US President.

She tweeted: “Extraordinary stuff. And huge litmus test for next PM – will he stand up for the ability of diplomats to do their jobs or give in to this kind of behaviour by the US President?”

Earlier Foreign Secretary Jeremy Hunt defended May, accusing the President of being “disrespectful and wrong” and said he would keep Sir Kim if he became PM.

He tweeted: “Friends speak frankly so I will: these comments are disrespectful and wrong to our Prime Minister and my country. Your diplomats give their private opinions to @SecPompeo and so do ours! You said the UK/US alliance was the greatest in history and I agree...

He went on: “But allies need to treat each other with respect as @theresa_may has always done with you. Ambassadors are appointed by the UK government and if I become PM our Ambassador stays.”

In the extraordinary onslaught against an ally, Trump attacked May over Brexit, accusing her of ignoring his advice and “going her own foolish way”.

He said: “The wacky ambassador that the UK foisted upon the United States is not someone we are thrilled with, a very stupid guy. 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.”

May has made clear her full support for Sir Kim following the leak of diplomatic dispatches in which he described the White House as “inept” and “dysfunctional”.

Downing Street said Sir Kim remained in post after Trump warned on Monday the White House would have nothing more to do with him. The first indication of that became evident when the ambassador was “uninvited” to a White House dinner on Monday evening, held in honour of the Emir of Qatar.

Sir Kim was also not attending a meeting yesterday between Ivanka Trump and the International Trade Secretary Liam Fox in Washington.

The issue was discussed at Cabinet, where May denounced the leak of Sir Kim’s dispatches as “unacceptable” and stressed it was important ambassadors were able to provide “honest, unvarnished” advice to ministers.