The US Speaker of the House Nancy Pelosi has warned that there will be "absolutely no chance" of a US-UK trade agreement passing the US Congress if Brexit undermines the Good Friday Agreement.

Responding to the latest Brexit developments, Speaker Pelosi issued a statement tonight praising the Good Friday Agreement as the bedrock of peace in Northern Ireland and an inspiration for the whole world.

"Whatever form it takes, Brexit cannot be allowed to imperil the Good Friday Agreement, including the stability brought by the invisible and frictionless border between the Irish Republic and Northern Ireland.

"The UK must respect the Northern Ireland Protocol as signed with the EU to ensure the free flow of goods across the border," Nancy Pelosi said.

"If the UK violates that international treaty and Brexit undermines the Good Friday accord, there will be absolutely no chance of a US-UK trade agreement passing the Congress," she added.

Earlier, Democratic Congressman Richard Neal told RTÉ News that he had raised concerns over the latest Brexit developments, and their implications for Northern Ireland, with Ms Pelosi.

Congressman Neal is the chairman of the House Ways and Means Committee which will oversee any future US-UK trade agreement.

"I spoke to Speaker Pelosi earlier this morning about what I saw as a threat that could jeopardise the success of the Good Friday Agreement," he said.

"She indicated that she is consistent with my view that any threat that would reimpose a border on the island of Ireland would negate any possibility of having a free trade bilateral agreement with the United Kingdom," he added.

Congressman Neal also spoke today to the Northern Ireland Secretary Brandon Lewis.

"The Secretary assured me that he saw no threat of re-establishing a border and he was steadfast in his belief that the Good Friday Agreement remained sacrosanct," Congressman Neal said.

A group of prominent Irish-Americans known as the Ad Hoc Committee to Protect the Good Friday Agreement, has also expressed concerns about the latest Brexit developments.

"Political leaders and trade negotiators may sabre rattle all they want as they seek to negotiate a much needed trade deal but the Good Friday Agreement cannot be viewed as a bargaining chip," according to a statement from the group.

Meanwhile, a foreign policy adviser to Joe Biden has said that the Democratic presidential candidate is committed to preserving the hard-earned peace and stability in Northern Ireland. 

In a tweet responding to the latest Brexit developments, Mr Biden's adviser Antony Blinken wrote: "As the UK and EU work out their relationship, any arrangements must protect the Good Friday Agreement and prevent the return of a hard border."

"I sincerely hope the British government upholds the rule of law and delivers on the commitments it made during Brexit negotiations, particularly in regard to the Irish border protocols," he added.

This is not the first time that Mr Biden and other senior Democrats have voiced support for the Northern Ireland peace process.

Last month, the Biden campaign held a virtual rally for Irish-American voters and Democratic Congressman Brendan Boyle told the event that the Brexit process had put hard-won peace and justice in Ireland at risk.

"We fortunately have many allies on Capitol Hill. One place that has not been an ally is the Oval Office," Congressman Boyle said.

"What a refreshing change it will be to have Joe Biden come this January. To have someone who supports the Good Friday Agreement and wants to protect it. Someone who is not mindlessly cheerleading for Brexit no matter the cost," he added.

Last November, while campaigning for the Democratic nomination, Mr Biden said he cared a great deal about the Northern Ireland peace process and that he would continue to put pressure on Britain to ensure there is no return to a hard border after Brexit.