Donald Trump has said a second Brexit referendum would be “unfair” before launching an extraordinary attack on Theresa May’s handing of negotiations.

The comments came just hours after he said his administration was looking forward to “negotiating a large scale trade deal with the UK” – having reportedly been lobbied to do so by Nigel Farage.

The former Ukip leader is said to have suggested the US president signal his support for the UK leaving the EU without a deal during a meeting in Washington this month.

“I’m surprised at how badly it’s all gone from the standpoint of the negotiation, but I gave the prime minister my ideas on how to negotiate it, and I think you would have been successful,” Mr Trump told reporters during a press conference at the White House with Irish taoiseach Leo Varadkar.

“She didn’t listen to that and that’s fine. She’s gotta do what she’s gotta do but I think it could have been negotiated in a different manner, frankly. I hate to see everything being ripped apart right now.

Trump and Farage - a working friendship Show all 7 1 /7 Trump and Farage - a working friendship Trump and Farage - a working friendship Donald Trump and Nigel Farage pose in the golden elevator at Trump Tower on 12 November 2016, four days after Trump was elected president. Farage was the first British politician to meet with Trump after the election LeaveEUOffical/Twitter Trump and Farage - a working friendship Not long after their meeting at Trump Tower, then-president elect Trump tweeted in favour of Nigel Farage being appointed ambassador to the US Trump and Farage - a working friendship Farage appears at a Trump campaign rally in Jackson, Mississipi on 24 August 2016. Farage drew parallels between the recent vote for Brexit in the UK and a vote for Trump in the US, saying "they could take back control of their country, take back control of their borders and get back their pride and self-respect" Getty Images Trump and Farage - a working friendship Trump introduced Farage as "Mr. Brexit" Getty Images Trump and Farage - a working friendship President Trump with Nigel Farage when they met met face-to-face to discuss why the President should back a no-deal Brexit on 3 March 2019 PA Trump and Farage - a working friendship From left to right: Gerry Gunster (US pollster and campaign adviser to Leave.EU), Arron Banks (Leave.EU founder who is being investigated over the funding of the Brexit campaign), Donald Trump (then president-elect), Nigel Farage (then leader of UKIP), Andy Wigmore (communication director of Leave.EU) and Raheem Kassam (then-advisor to Farage and later UK editor of Breitbart news) Trump and Farage - a working friendship Farage and his adviser Raheem Kassam arrive to meet with Trump on November 12 2016 Getty Images

“I don’t think another vote would be possible because it would be very unfair to the people that won, they’d say, ‘What do you mean you’ve gotta take another vote?’ So that would be tough.”

Sitting alongside Mr Varadkar, Mr Trump took credit for predicting Brexit ahead of the 2016 vote, and told a story he has repeated before about golfing in Scotland the day before the vote, and telling people, “I think it’s going to happen”.

In fact, Mr Trump was at his Turnberry golf course the day after the vote, and does not appear to have offered a prediction the day before.

He also claimed former president Barack Obama predicted the UK would remain in the bloc. Although Mr Obama opposed voting leave, he does not appear to have made a prediction publicly.

Mr Trump described this week’s deadlock in parliament as a “tough situation” that was happening for “no reason”, before acknowledging the Irish border was “one of the most complex points”.

Asked if he thought Brexit day – currently set for 29 March – should be delayed, Mr Trump appeared to suggest it should.

“Well I think they’re probably gonna have to do something because right now they’re in the midst of a very short period of time. The end of the month, and they’re not gonna be able to do that,” he said.

“But I would like to see, I’d like to see that whole situation with Brexit work out.”

'You might have to tell the world what's happening, because nobody knows' President Trump says Brexit is 'tearing a lot of countries apart'

He said the US would be able to do “a very big trade deal with the UK”, before claiming his administration was “renegotiating our trade deal with the European groups – literally individual nations and also the whole”.

His comments came just hours after the European parliament failed to endorse opening trade talks with America, amid fears over Mr Trump’s trade and environmental policies.

But Mr Trump threatened to “do something pretty severe economically” if the EU “don’t talk to us”.

“We’re gonna tariff a lot of their products coming in, because the European Union treats us very very unfairly,” he said.

A significant trade deal with the US has often been cited by those in favour of Brexit as grounds for the UK leaving the EU – with some suggesting it would mitigate the substantial economic damage such an eventuality is expected to cause.

Critics, however, have cautioned any agreement would likely results in lower food, agriculture and environmental standards.