A minister suggested Joe Biden does not «fully appreciate» the details of the row surrounding the Northern Ireland Protocol.
Speaking to Kay Burley on Sky News, Environment Secretary George Eustice said the row over post-Brexit arrangements between the UK and the EU was «very complicated» and «I’m not sure he fully appreciates it all».
«It’s possible that at the moment he’s just reading the headlines, reading what the EU says, reading what Ireland might say, which is that they would like the Northern Ireland Protocol to work the way the EU envisions,» he continued.
«We think he’s wrong because the truth is that unless we have a sustainable solution that enables trade to continue between Britain and Northern Ireland, we will have problems, and that in and of itself will be a challenge to the Belfast Agreement.»
Mr Eustice said it was «legitimate for him to have an opinion and express that opinion» and added: «Obviously we are going to effectively explain to the United States that it is tantamount to saying that potatoes grown in one part of the United States can» be sold in part. Another from the United States.
«When you explain some of these provisions in detail, the US government understands that this is clearly meaningless and therefore needs to be reconsidered.»
Since Mr Eustice’s interview, government sources have told Sky News that the number 10 position is that the EU is wrong about the protocol, not the US.
A source said: «What he meant to say is that we agree with the US that there is nothing that should undermine the Belfast Agreement.
«We want to come up with the most sustainable solution, not necessarily the one proposed by the European Union.»
The environment secretary was speaking hours after Prime Minister Boris Johnson met Biden at the White House.
The president, speaking alongside the prime minister in the Oval Office, issued a warning that the protocol dispute must not end with a «closed border» on the island of Ireland.
«On the [Northern Ireland] I feel very strongly about these protocols. We’ve spent a tremendous amount of time and effort, United States, it’s been a great bipartisan effort.»
«And I absolutely would not like to see, nor can I add that many of my fellow Republicans would like to see a change in the Irish Accords, and the end result is a closed border in Ireland.»
The protocol is a key part of the Brexit deal struck between London and Brussels, and is designed to avoid the difficult border on the island of Ireland.
As part of this arrangement, Northern Ireland remains subject to some EU rules, and there are checks on goods entering Northern Ireland from Great Britain.
Some opponents of the protocol, including the Northern Ireland Democratic Unionist Party, want it to be scrapped entirely.
Others argue that the problems can be fixed without abandoning the protocol.
Brexit Minister Lord Frost said in July that «significant changes» must be made to the protocol and unveiled proposals from the UK government aimed at achieving what he said would be a «new balance» for the protocol.