A US Democratic Congressman and ally of President Joe Biden has accused the British government of showing "wanton disregard" for international law in Northern Ireland and says the issue could impact a future US trade deal.
Congressman Brendan Boyle, a member of the House of Representatives Ways and Means Committee, which has responsibility for US trade deals, was speaking after attending a meeting of the US Congress' influential Irish-American caucus on the issue yesterday.
The meeting was addressed by EU Commission Vice President Maros Sefcovic and Irish Foreign Minister Simon Coveney.
The European Union last week said it would take legal action after the British government unilaterally extended a grace period for checks on food imports to Northern Ireland, a move Brussels said violated the terms of Britain's Brexit divorce deal.
The British government has said the measures were necessary and proportionate and did not violate the deal.
"There are many members of Congress, and they were on the call yesterday, who share my deep concern and real shock at the wanton disregard for international law being displayed by some in London," Boyle told Ireland's RTE radio when asked about the grace period extension.
"Certainly the continued provocations around the Northern Ireland Protocol, obviously make it very difficult to commence a US-UK trade deal," said Boyle.
The fate of Northern Ireland, closely watched by the Biden administration, has been the most bitterly contested Brexit issue.
While campaigning in the presidential election last year, Biden warned Britain that it must honour Northern Ireland's 1998 peace agreement as it withdrew from the EU or there would be no separate US trade deal.
The chairman of the Ways and Means Committee, Richard Neal, on Wednesday told BBC television that Britain's move had "bothered" many in Congress due to its unilateral nature, which he said threatened the goodwill established by the 1998 deal.
London ultimately agreed a protocol that left the British-run province aligned with the EU's single market for goods when it exited the bloc's orbit. This necessitates checks on some items arriving there from other parts of the United Kingdom.