The DUP has said that Boris Johnson's new Brexit bill is "a step forward for Northern Ireland" but leaves serious issues unaddressed.
However, Sinn Fein said the Government had "a brass neck" and the British cabinet did not care what happened here.
The parties were giving their response to the new UK Internal Market Bill which over-rides key elements of the Brexit deal Mr Johnson signed with Brussels.
The Taoiseach "set out in forthright terms" his concerns to Mr Johnson over the latest developments on Brexit.
Micheál Martin spoke to the Prime Minister for over half an hour on the telephone.
And in the Dail, Mr Martin accused the UK of acting in bad faith.
"Proper negotiations are conducted on a 'no surprise' basis ... and to drag Northern Ireland back into this is extremely divisive - and dangerous," he said.
"This statement undermines trust. There was no 'heads-up' on this, so to speak. It represents a very new departure in terms of international relations."
And on Wednesday night, US house speaker Nancy Pelosi reiterated her warning that there would be dire consequences if the UK's move threatened the Good Friday Agreement.
"The UK must respect the Northern Ireland protocol as signed with the EU to ensure the free flow of goods across the border," she said.
"If the UK violates that international treaty and Brexit undermines the Good Friday accord, there will be absolutely no chance of a US-UK trade agreement passing the Congress."
But DUP MP Sammy Wilson gave a cautious welcome to the proposals.
He said: "This bill is a step forward and a recognition by the Government of the defects of the Northern Ireland protocol and its potential impact on the internal market of the whole of the UK, but more work is required.
"We will take time to fully consider the effects of the bill but there is still more work to be done with regards to state aid and other issues."
Earlier, Arlene Foster said the DUP would be working to try and change the Northern Ireland protocol.
She said it was vital that local businesses had unfettered access to the UK market.
But Deputy First Minister Michelle O'Neill said: "The British Government has a brass neck.
"(Northern Ireland Secretary) Brandon Lewis and the entire British cabinet do not care about what happens to us in the north.
"They have demonstrated that time and time again, they are prepared to use us here in the North as a pawn in the Brexit negotiations."
The Sinn Fein vice-president added: "This is an international agreement which was painstakingly struck after months of negotiations. It contains unique protections in the Irish protocol but now the British Government is saying it is prepared to override it. That is not acceptable."
Ulster Unionist leader Steve Aiken said: "The publication of this bill doesn't provide much comfort for those of us who consider the EU Withdrawal Agreement an awful document which attacks the foundations of the Belfast Agreement, undermines the integrity of the UK and leaves us in economic limbo."
The European Commission called for urgent talks with London. Commission president, Ursula von der Leyen, said she was "very concerned" following the tabling in Parliament of the UK Internal Market Bill, which ministers have admitted will breach international law.
As talks continued in London on a post-Brexit free trade agreement, she said such actions would "undermine trust" and called on the Prime Minister to honour his past commitments.
Ms von der Leyen's warning came as Sir John Major became the latest senior Conservative to denounce Mr Johnson's decision to go back on assurances he had made in an internationally binding treaty.
"For generations, Britain's word - solemnly given - has been accepted by friend and foe. Our signature on any treaty or agreement has been sacrosanct," the former prime minister said in a statement.
"If we lose our reputation for honouring the promises we make, we will have lost something beyond price that may never be regained."
Ministers have argued legislation is necessary to protect the Northern Ireland peace process if the two sides are unable to agree a free trade deal before the current Brexit transition period runs out at the end of the year.
However, European Commission vice president Maros Sefcovic said he was seeking an urgent meeting of the joint EU-UK committee on the Brexit Withdrawal Agreement to enable the British to "elaborate" on their plans.