The European Union told Britain on Thursday it should urgently scrap a plan to break their divorce treaty but Prime Minister Boris Johnson's government refused and instead pressed ahead with a draft law that could sink four years of Brexit talks.
With chances of a messy end to Britain's departure from the EU growing, the European Commission said London would be committing "an extremely serious violation" of last year's withdrawal agreement if it went ahead with proposed legislation.
After emergency talks between Commission Vice President Maros Sefcovic and Britain's Brexit supremo Michael Gove, the EU said Britain's proposal has "seriously damaged trust" which London must now take steps to re-establish.
'Pressing Ahead With The Plan'
But the government made clear it was pressing ahead with the plan, saying the bill would be debated on Monday and publishing a legal opinion saying that the British parliament was sovereign and so could effectively do as it wished.
"Parliament is sovereign as a matter of domestic law and can pass legislation which is in breach of the UK's Treaty obligations. Parliament would not be acting unconstitutionally in enacting such legislation," the government's legal opinion said.
EU diplomats and officials said the bloc could use the Withdrawal Agreement to take legal action against Britain, though there would be no resolution before the end-of-year deadline for Britain's full exit from a transition period.
The British government says it is committed to the treaty and that a proposed law overriding parts of the Withdrawal Agreement merely clarifies ambiguities. Its main priority, it says, is the 1998 Northern Irish peace deal that ended decades of violence.
French Foreign Minister Jean-Yves Le Drian told his British counterpart Dominic Raab that a violation of the withdrawal agreement with EU would be "unacceptable", a spokeswoman said.