Sinn Féin, the SDLP and Alliance have warned Boris Johnson against reneging on his Brexit deal amid reports he plans to override the NI Protocol.
The Financial Times reported the UK plans new legislation to end the legal force of customs arrangements that were designed to avoid a hard Irish border.
NI Deputy First Minister Michelle O’Neill, of Sinn Féin, said that would be a “treacherous betrayal”.
SDLP leader Colum Eastwood said ripping up the EU deal would threaten peace.
While it would be “an act of bad faith so egregious as to make any country think twice about doing deals with the UK,” said Alliance leader Naomi Long.
Government sources told the BBC that the legislation would be introduced this week, describing it as a “sensible fall-back option” in case negotiations with the EU break down on the implementation of the NI deal.
UK Environment Secretary George Eustice told the BBC’s Today programme the government was “committed to implementing the NI Protocol”.
“There are negotiations ongoing through something called the joint committee process that Michael Gove [Cabinet Office Minister] is leading, a separate process to the main negotiation on a future trade agreement,” he said.
“It has always been recognised that that joint committee process was needed to iron out a few remaining technical details as to how the Northern Ireland Protocol would work.
“And it may well be the case that once that joint committee process itself has concluded there remain one or two loose ends where there is a requirement for legal certainty where the government may therefore need to legislate to provide that legal clarity and certainty.”
Mr Eustice added: “What happens to the Ireland and Northern Ireland border is not in doubt, that is clear that there are no checks and no border infrastructure at all.”
Northern Ireland What is the Northern Ireland Protocol?
The Northern Ireland Protocol was added to the EU Withdrawal Deal late last year, after more than three years of negotiations on how to prevent new customs checks along the land border in Ireland.
Under the protocol, Northern Ireland would leave the EU customs union with the rest of the UK at the end of this year, but would continue to enforce the EU’s customs code at its ports.
Northern Ireland would also stay in the EU Single Market for goods, meaning some new checks on products entering NI from GB.
Details on the nature and extent of goods checks at Northern Ireland ports are still to be agreed but unionist parties are strongly opposed to the protocol, fearing it damages the UK union.
In a statement on Monday, Ms O’Neill said Sinn Féin’s priority was to “avoid any border on the island of Ireland and to protect the peace process, Good Friday Agreement and all-Ireland economy”.
“This must also remain a top priority for the EU and its member states and therefore ensuring the full and urgent implementation of the protocol which provides these safeguards is paramount,” she added.
Mr Eastwood said overriding the EU deal “could see the return of a hard border in Ireland” and threaten the peace and stability built up over decades in Northern Ireland.
The Northern Ireland part of the Brexit deal, known as the Protocol, was agreed in October last year.
It is designed to prevent a hard border in Ireland – or even any new checks at the Irish border.
It does this by effectively keeping Northern Ireland in the EU’s single market for goods.
This will mean products entering Northern Ireland from the rest of the UK will be subject to new checks and control – the so-called Irish Sea border.
However, the precise nature of these checks needs to be agreed by the EU and UK and are being negotiated in parallel with the trade talks.
The government says it is still committed to the Protocol but it could make its own decisions on how it is implemented if it cannot reach agreement with the EU.
Mr Eastwood also said that if the prime minister reneged on a deal he signed just last October, it would “shred the British government’s international credibility”.
“It’s absolutely astonishing that any government who says that they want to go and do trade deals around the world would just rip up an agreement that they made a few months ago with the European Union,” he told BBC Radio Four.
Alliance leader Naomi Long said if reports of the plans were true, it would have “consequences far beyond the protocol”.
“It not only torpedoes any chance of a deal with the EU, but would be an act of bad faith so egregious as to make any country think twice about doing deals with the UK,” she said on Twitter.
President of the EU Commission Ursula von der Leyen said she trusted the UK government to implement the deal.
In a tweet, she said it was “essential to protect peace” on the island of Ireland.
The Irish Minister for Foreign Affairs Simon Coveney described the reports as “a very unwise way to proceed”.
Northern Ireland Unionist opposition
However, Northern Ireland’s biggest unionist parties have opposed the Northern Ireland Protocol since it was introduced, saying it would create an economic border in the Irish Sea.
They fear it will damage the union as Northern Ireland businesses will be treated differently from those in Great Britain.
First Minister and DUP leader Arlene Foster had argued against the protocol but days ago she told Sky News that Mr Johnson’s deal won the support of Parliament and was now the “law”.
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But on Sunday, the DUP’s Brexit spokesman Sammy Wilson struck a markedly different tone from his leader, saying the party “will not accept” the EU Withdrawal Agreement.
In a statement, released before news the government was planning new legislation broke, the UUP leader described the protocol as “potentially disastrous economically and constitutionally for Northern Ireland”.
“We won`t be able to trade within our own country without jumping through legislative hoops dictated by the EU and meekly accepted by the Conservative government,” Steve Aiken said.
On Monday morning he tweeted that “any moves on removing impact of Irish Sea Border will be very welcome”.
Traditional Unionist Voice (TUV) party leader Jim Allister said the Withdrawal Agreement tears “at the very fabric of the union”.
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