The DUP has cautiously welcomed reports that the Government could abandon commitments it made to Brussels on Northern Ireland in its Brexit deal.
The leaders of Stormont's four pro-Remain parties have said that abandoning elements of the Northern Ireland protocol would seriously undermine the Good Friday Agreement.
Michelle O'Neill, Colum Eastwood, Naomi Long and Clare Bailey were speaking after Downing Street said that new Brexit legislation was needed to protect the peace process in case Britain can't secure a free trade deal with the EU.
But on Monday night the DUP said that while it awaited details of the proposed legislation, it appeared to be a positive move.
In a statement not attributed personally to any MLA or MP, the party said: "We note the speculation that the Government will pursue fall-back measures under the internal market bill to protect Northern Ireland's interests should a deal not be agreed that mitigates the threat of the Northern Ireland protocol. We will want to see the finer details and clauses relating to this and will study them carefully.
"We welcome them in broad terms in so far as they go, but the Government must continue to work to remove any disadvantages to Northern Ireland brought about by its signing up to the protocol."
Senior figures in Brussels reacted with dismay after it was reported that the Government will table new legislation that could override key elements of the Withdrawal Agreement which sealed the UK's departure from the EU in January.
Boris Johnson has set a five-week deadline for talks on a free trade deal to reach an agreement, or for both sides to accept there will be no deal when the current transition period ends in December.
Northern Ireland pro-Remain parties voiced grave concern at the prospect of the Prime Minister introducing domestic legislation to supersede parts of the protocol governing state aid and customs arrangements.
They said: "It is entirely unacceptable to the Northern Ireland parties that the UK Government would seek to abandon these safeguards and mitigations, which we believe would amount to a serious betrayal of an existing international treaty. The economic and political impact on the island of Ireland, on the UK, and above all on the people whom we represent, would be devastating and long-lasting.
"It would represent a shocking act of bad faith that would critically undermine the Good Friday Agreement political framework and peace process and the UK's ability to secure other crucial deals to protect the Northern Ireland economy."
The parties called on the Government to "honour its commitments" and ensure that the protocol is implemented rigorously. Under the protocol, Northern Ireland will continue to follow single market rules for goods and administer the EU's customs code at its ports. It was designed to avoid a hard border on the island of Ireland, but unionists oppose it, arguing that it creates an economic border between Northern Ireland and Britain.
UUP leader Steve Aiken said: "Nobody should be in any doubt that the Northern Ireland protocol is the worst of both worlds economically and constitutionally for Northern Ireland. It attacks the very foundations of the Belfast Agreement and should be amended.
"If there is any chance to change it, it should be changed."
Sinn Fein president Mary Lou McDonald said: "I am deeply concerned that British Prime Minister Boris Johnson would step away from an international obligation like this. To do so would show total disregard for the lives and concerns of the people of Ireland. Throughout the sorry saga of Brexit, Sinn Fein have been very clear that Ireland cannot become collateral damage to the posturing of the British Government in this Tory Brexit."
The Irish Government has conveyed its concerns to London. Minister for Foreign Affairs Simon Coveney said if the UK introduced domestic legislation that undermined commitments made in the Withdrawal Agreement it would be a very serious breach of trust.
However, the Prime Minister's official spokesman said the Government was proposing only "limited clarifications" to the law to ensure ministers can preserve the gains of the Good Friday Agreement in the event of no deal.
The Internal Market Bill, to be tabled on Wednesday, will ensure goods from Northern Ireland continue to have unfettered access to the UK market while making clear EU state aid rules - which will continue to apply in Northern Ireland - will not apply in the rest of the UK.