A senior Tory has renewed threats to tear up Boris Johnson's Brexit deal which he warned was putting stability in Northern Ireland in peril.
Deputy Prime Minister Dominic Raab said the Government would take "whatever measures are necessary" to resolve issues around the Northern Ireland Protocol, a key part of the agreement Mr Johnson signed.
Labour's Lisa Nandy said the "lack of trust in the Prime Minister himself is part of what is fuelling this crisis in Northern Ireland".
Tensions have mounted over the mechanism, which was designed to prevent a hard border on the island of Ireland - the UK's only land frontier with the EU.
Instead, the protocol effectively creates a border down the Irish Sea, with businesses struggling with red tape on goods travelling between Britain and Northern Ireland.
Mr Raab teed up a fresh confrontation with Brussels by threatening to tear up the protocol without agreement from the EU.
He said rewriting the deal "can't be put off" following Sinn Fein's historic victory in the Northern Ireland Assembly elections.
Mr Raab said the Government would take "whatever measures are necessary" to resolve the issues and warned stability was being "imperilled" by problems with the protocol.
Asked if the UK would act unilaterally, he told Sky News: "We are clear that that option has not been taken off the table.
"We’d prefer to get it resolved through negotiation, that’s why we have been through a protracted period to try and get it fixed through negotiation but as you know, there are measures that we can take to make sure that we deal with the problem.
"We can’t put it off and it is clear now, and if anything, the outcome in Northern Ireland from those elections makes it clear, it can’t be put off."
But Mr Raab refused to say if there would be legislation in the Queen's Speech on Tuesday - something Boris Johnson has previously hinted at.
Shadow Levelling Up Secretary Lisa Nandy said the election result was significant but Labour would fight to protect the integrity of the UK
She warned: " Boris Johnson is not seen as an honest broker, he is the person who helped to write the architecture of this problem rather than resolve it.
"I think the key over the next couple of weeks for the Government is that they've got to get on and resolve these issues around the Northern Ireland Protocol because at the moment, I have to say the lack of trust in the Prime Minister himself is part of what is fuelling this crisis in Northern Ireland."
Sinn Fein has become the largest party at Stormont for the first time, with vice president Michelle O'Neill in line to become First Minister.
But the result created fresh political uncertainty in Northern Ireland as the unionist DUP, the second largest party, has ruled out forming a powersharing executive unless there are major changes to the protocol.
Under the terms of the Good Friday Agreement, which protects peace in Northern Ireland, unionists and nationalists must be represented for the executive to function.
Sinn Fein is committed to a border poll on unification with Ireland, although it is unlikely in the short term.
"If you look at the results in Northern Ireland, 58% fully of people voted either for parties who support the Union or for parties who do not support constitutional change and that is the message from the people of Northern Ireland," Mr Raab told Sky News.
"We don't have an executive yet, I think the first priority, mindful of that 58% of people in Northern Ireland who are not calling for that kind of change, is to get the executive up and running."
Ireland's Europe minister Thomas Byrne said "a decisive majority" of the MLAs elected to Stormont want to make the protocol work and called on the UK to "engage in a renewed way with the European Union " on the issue.
Meanwhile, Northern Ireland Secretary Brandon Lewis will meet with the leaders of the Stormont parties on Monday to talk about resurrecting the Assembly.
