UK foreign minister James Cleverly told US secretary of state Antony Blinken that Britain's top priority was to protect the Good Friday Agreement, a government spokesperson said on Wednesday.
"He [Cleverly] explained the Protocol is, however, causing real problems in Northern Ireland which we must fix,” the spokesperson said in a statement.
Cleverly met with Blinken at the UN’s General Assembly in New York on Tuesday, ahead of a planned meeting between the US president and the British prime minister on Wednesday.
The White House said Joe Biden will tell Liz Truss she must work with the EU to find a negotiated outcome to solve post-Brexit tensions over the Northern Ireland Protocol.
Ms Truss declined to discuss the protocol with France’s Emmanuel Macron on Tuesday, and it is unclear if she will raise it with European Commission president Ursula von der Leyen.
But US national security adviser Jake Sullivan made it clear Mr Biden will discuss it “in some detail” with Ms Truss.
Ms Truss is pushing ahead with her controversial Northern Ireland Protocol Bill, that the EU and other critics say will breach international law by suspending elements of the agreement.
There have also been suggestions she could unilaterally trigger Article 16 of the protocol, to override parts of the agreement brokered as part of the Brexit divorce deal.
Mr Sullivan told reporters the president “will encourage the UK and the European Union to work out an effective outcome that ensures there is no threat to the fundamental principles of the Good Friday Agreement”.
“And he will speak in some detail to her about that,” he added.
The adviser said Mr Biden will “communicate his strong view that the Good Friday Agreement – which is the touchstone of peace and stability in Northern Ireland – must be protected.
“And we must collectively take steps – the US, the UK, the parties in Northern Ireland, the Republic of Ireland – to ensure that it is protected,” he added.
Ms Truss’s official spokesman said on Tuesday that the protocol is an issue “we want to resolve this with the EU” when questioned why she did not discuss it with Mr Macron.
He accepted Ms Truss’s prediction that a comprehensive US-UK trade deal, which Brexit supporters touted as a major prize of leaving the EU, is years away.
Ms Truss had told reporters: “There aren’t currently any negotiations taking place with the US and I don’t have an expectation that those are going to start in the short to medium term.”
Mr Biden was meant to hold talks with Ms Truss in the UK as he visited to attend Queen Elizabeth’s funeral, but they were delayed until Ms Truss’s US trip.
