The DUP will table amendments to Prime Minister Boris Johnson's Internal Market Bill, Sammy Wilson has confirmed.
The East Antrim MP said that while the bill was "far from perfect", "it is a massive step forward for businesses in Northern Ireland".
Mr Wilson also criticised an intervention from former prime ministers Sir John Major and Tony Blair who wrote in The Sunday times that the bill "puts the Good Friday Agreement at risk".
The Conservative and Labour grandees united to condemn Boris Johnson's Brexit legislation, saying it could have a devastating effect on the peace process, trade negotiations and the UK's integrity.
Both men paid a key role in the signing of the agreement and both backed the UK remaining in the European Union.
"It negates the predictability, political stability and legal clarity that are integral to the delicate balance between the north and south of Ireland that is at the core of the peace process," they wrote.
"This has wide-ranging ramifications. It will not only make negotiation with the EU more difficult, but also any trade negotiations with other nations, including the United States. Once trust is undermined, distrust becomes prevalent.
"We both opposed Brexit. We both accept it is now happening. But this way of negotiating, with reason cast aside in pursuit of ideology and cavalier bombast posing as serious diplomacy, is irresponsible, wrong in principle and dangerous in practice.
"It raises questions that go far beyond the impact on Ireland, the peace process and negotiations for a trade deal - crucial though they are. It questions the very integrity of our nation."
In response Mr Wilson said the agreement contains only one mention of Northern Ireland's border with the Republic, which "relates to demilitarisation which has already happened".
"I don’t know of anyone calling for the army to rebuild those installations on the border," the East Antrim MP said.
"The Belfast Agreement however is about respecting consensus something which the Withdrawal Agreement ignored and drives a coach and horses through.
"Blair and Major were less outspoken about the impact of a trade border between Northern Ireland and the rest of the United Kingdom despite its obvious impact on our economy and relationships in Northern Ireland.
"The Internal Market Bill is far from perfect and that’s why we will table amendments to the Bill. The suggestion by the hero of the peace process brigade that the Bill rips apart the Belfast Agreement is complete and utter bunkum without any factual basis."
The veteran DUP politician said "the Internal Market Bill as published is not the finished product but it is massive step forward for business in Northern Ireland".
His comments were echoed by TUV leader Jim Allister who said "the Belfast Agreement says nothing adverse to checks on goods at the border".
"It gives no such guarantee, but what it does purport to guarantee, namely, acceptance of Northern Ireland as an integral part of the UK, is the very thing Blair and Major are wanting to trash, without the consent that the Belfast Agreement was supposed to entrench," the North Antrim MLA said.
UUP leader Steve Aiken said while the withdrawal agreement was bad for Northern Ireland, Mr Johnson's bill was not the answer.
"The UUP position has and continues to be that there should be no impediments to trade, North South, West and East, and above all, within our own nation – first and foremost we need a level playing field across the UK," he said.
“The Internal Market Bill, for all the bluster and hype on all sides, does not address this fundamental issue. The biggest commitment that can be made to the Belfast Agreement is to ensure that there are no barriers installed on these islands. That should be the focus of both EU and UK negotiators."
Sinn Fein MLA Caoimhe Archibald accused the UK Government of acting in "bad faith" and called for the Assembly to debate the bill on Monday.
In an article for The Telegraph, Mr Johnson said Brussels was threatening to use an "extreme interpretation" of the Northern Ireland Protocol to impose "a full-scale trade border down the Irish Sea" that could stop the transport of food from Britain to Northern Ireland.
Irish Foreign Minister Simon Coveney said on Sunday there may be "limited checks" on goods coming from Great Britain into the region because there is an agreement to prevent the need for physical infrastructure on the Irish border.
The measures were envisaged to stop goods passing from England, Scotland or Wales into the Republic of Ireland via Northern Ireland tariff-free if no wider agreement is struck between the EU and UK.
"There is no blockade proposed," Mr Coveney told the BBC.
"That is the kind of inflammatory language coming from Number 10 which is spin and not the truth."
The European Commission has given the UK until the end of the month to drop legislation enabling ministers to override the provisions in the Brexit Withdrawal Agreement relating to Northern Ireland.
Following a stormy meeting in London on Thursday, the commission warned the UK was putting trade talks at risk and said it would "not be shy" of taking legal action.
The Prime Minister's official spokesman, however, reiterated the Government's position that the provisions in the Internal Market Bill remained "critical" to the preservation of the Northern Ireland peace process.