The UK government has been accused of "self-defeating strategy" after a report suggested it was planning to introduce new laws that would allow it to override parts of the Brexit Withdrawal Agreement.
According to the Financial Times, the Internal Market Bill would enable the government to "eliminate" areas of the deal in areas such as state aid and customs checks in Northern Ireland.
New customs arrangements in Northern Ireland were designed to prevent checks at the border with the Republic of Ireland and maintain the Good Friday Agreement.
Northern Ireland Deputy First Minister Michelle O'Neill said such a move would be a "treacherous betrayal which would inflict irreversible harm on the all-Ireland economy and the Good Friday Agreement".
With the EU adamant that respecting the Withdrawal Agreement is key to securing a trade deal before the end of the year, an EU diplomat said the UK was following a "self-defeating strategy".
A government spokesperson told the BBC that the move was "not intended to derail the talks", and stressed that the UK will continue to negotiate with the EU in good faith.
Prime Minister Boris Johnson is claiming the Internal Market Bill is effectively a backup plan, should he fail to secure a deal with the EU. And, he has set an unofficial deadline of 15 October to get that deal done by. The eighth round of negotiations begin in Brussels on Tuesday.
Labour's Jonathan Ashworth told BBC Radio 4's Today programme: "Boris Johnson, I thought, told us he had an oven-ready deal. And he fought a general election telling us he had an oven-ready deal. [This] now suggests that he was misleading people in that general election.
"And Parliament supported the Withdrawal Agreement earlier on this year. He has made promises and signed a treaty around these arrangements for Northern Ireland, and he now seems to be backing out of that."