he UK/US rift over Brexit escalated on Wednesday as a Cabinet minister claimed Joe Biden was “wrong” over key details of the trade arrangements with Northern Ireland – and said a trade deal between the two countries was “not a priority” for the president.

Environment Secretary George Eustice also alleged that the US president does not “fully appreciate” the Northern Ireland Protocol which is a “very complicated piece of agreement”.

Amid the transatlantic stand-off, Mr Eustice did not rule out the Government failing to strike a post-Brexit trade deal with the US before the next General Election, expected in 2024.

He admitted it was not a “priority” for the White House.

Mr Biden poured cold water on prospects of a quick post-Brexit trade deal on Tuesday.

In a blow to Boris Johnson, the US president did not counter the assertion from his predecessor Barack Obama’s that Britain would be at the “back of the queue” for a post-Brexit free trade agreement.

He also issued a fresh warning for the UK not to damage the peace process in Northern Ireland as it rows with Brussels over trade links across the Irish Sea.

However, Mr Eustice claimed on Wednesday that the US president had not fully understood the details of the Northern Ireland Protocol.

“It’s a very complicated piece of agreement, the Northern Ireland Protocol, I’m not sure he does fully appreciate all of that,” he told Sky News.

He added: “I think he is probably at the moment just reading the headlines, reading what the EU is saying, reading what Ireland might be saying, which is they would like the Northern Ireland Protocol to work in the way that the EU envisgage.

“We think he is wrong because the truth is unless we have a sustainable solution that enables trade to continue between GB and Northern Ireland, then we are going to have issues, that itself would become a challenge to the Belfast Agreement.”

He also argued: “We will obviously explain to the United States that effectively what is tantamount to saying that potatoes grown in one part of the United States can’t be sold in another part of the United States.”

Brexiteers trumpeted a trade agreement with America as a key part of their campaign during the 2016 referendum and Boris Johnson signed the Northern Ireland Protocol, on trade with mainland Britain, despite warnings that it could endanger the peace on the island of Ireland.

Mr Eustice could not guarantee that a trade deal with the US will be struck before the next General Election, expected eight years after the country voted Out.

“President Biden has always been clear that trade deals are not really a priority for him at the moment,” said the Cabinet minister, a leading Brexiteer.

He added: “We still very much hope to be able to put together an agreement with the United States.”

Pressed by presenter Kay Burley on when, he responded: “We are not putting timescales on it, it’s always better to get an agreement.”

Asked if it would happen before the next election, he replied: “We don’t need one before the next election but obviously we would like one.”

Questioned whether he was confident of such a result, he added: “We are confident that we will get one at some point. But it’s just not a priority for the US administration.”

Sitting next to Mr Johnson in the Oval Office on Tuesday, Mr Biden made clear that a Brexit trade deal with the US was not currently on the cards.

He told reporters: “We’re going to talk a little bit about trade today and we’re going to have to work that through.”

As hopes of a trade deal faded, UK ministers were understood to be instead considering whether to join an existing pact with the US, Mexico and Canada to boost trans-Atlantic trade in a major departure from their prior ambitions.

However, it was not clear whether Washington would agree to such a move.

Downing Street said brokering a comprehensive deal with the White House remains “the priority” but did not rule out joining other pacts as a back-up.

“Our focus is on the US stand-alone deal and that’s what we’re working towards,” the Prime Minister’s official spokesman said.

Mr Johnson updated the president on the “developments” on the Northern Ireland Protocol since their meeting in Cornwall in June.

Vocally proud of his Irish heritage, Mr Biden said he feels “very strongly” about the issues surrounding the peace process, as problems with the Northern Ireland Protocol persisted.

“And I would not at all like to see, nor I might add would many of my Republican colleagues like to see, a change in the Irish accords, the end result having a closed border in Ireland,” he said.

Mr Johnson said “that’s absolutely right”, adding: “On that point, Joe, we’re completely at one, nobody wants to see anything that interrupts or unbalances the Belfast/Good Friday Agreement.”

But in one possible boost to trans-Atlantic trade, Mr Biden said they are “going to be working on lamb” – with imports currently banned from Britain.

The US president said he was “anxious” to attend the Cop26 climate summit in Glasgow “with bells on”, and said they would continue talks on how to co-operate on Afghanistan.

Mr Biden presented the Prime Minister with a framed photo of their first meeting in Carbis Bay during the G7 Summit and a White House-branded watch, Downing Street said.

And Mr Johnson gave the president a signed copy of astronaut Tim Peake’s book “Hello, Is This Planet Earth?”, with an inscription expressing hopes the book “provides a reminder of what we’re fighting to save as our countries tackle climate change together”.

The Prime Minister first held talks with vice president Kamala Harris after arriving in Washington DC by train from New York, where he has been attending a UN summit.