Arlene Foster has said that the DUP will be working to try and change the NI Protocol included in the Withdrawal Agreement, adding that it is important Northern Ireland has unfettered access to the UK market.
The First Minister was speaking as the Government published its Internal Market Bill, which Downing Street said was designed to provide a "safety net" for Northern Ireland businesses if talks with the EU on a free trade agreement fail.
Critics have argued, however, it gives ministers the power to override parts of the Withdrawal Agreement, in particular the Northern Ireland protocol.
Northern Ireland Secretary Brandon Lewis caused an uproar on Tuesday when he admitted in the Commons that the bill would break international law in a "very specific and limited" way.
Speaking in Co Tyrone, Arlene Foster referenced previous comments she made stating she recognised that the Northern Ireland Protocol was now law.
"In an interview a couple of weeks ago, I said we would obey the law and as ministers it is our legal duty to make sure that we look to the law, but that doesn't stop us from trying to change the law," she said.
"I will be working will all my colleagues in the DUP to try and ensure we listen to the voices of businesses and we make sure that we represent that voice.
"It's important that we have unfettered access and that we have a UK market that we can operate in without any discrimination and make sure our wonderful firms are able to continue to work."
Asked about the comments made by Brandon Lewis, Mrs Foster added: "Those are matters for the ministers in Whitehall and in Westminster. For us here in Northern Ireland we have to make sure that we represent the interests of companies so we can continue to do business in the Great Britain market.
"It's important we continue to make the case for clarification, for changes where necessary so that we can move ahead."
Michelle O'Neill has accused Brandon Lewis of having a "brass neck".
"I think it demonstrates again that Brandon Lewis and the entire Tory Government do not care what happens to the people who live in the north of Ireland," the Deputy First Minister said.
"They have demonstrated time and time again that they are quite happy to use us as a pawn in the middle of the Brexit debate.
"There was an international agreement painstakingly struck, and we got ourselves some protection in the form of the protocol and what Brandon Lewis openly said was, 'but sure that doesn't matter anymore we are going to override that'.
"It's not acceptable to the EU side.
"I spoke to Simon Coveney this morning, he shares the view that it is not acceptable, that it won't be tolerated.
"If they stand any chance of negotiating a future trade deal, who wants to do a deal with someone who reneges on a previous deals they have made?"
Ms O'Neill called for the Irish Government to put it firmly to the UK Government that it "must adhere" to the international agreement.
"They have to fight very hard for our interests," Ms O'Neill added.
"We have fought very hard for the last three-and-a-half years since the Brexit debate started to protect the Good Friday Agreement, to make sure there is no hard border on this island and to protect our all-island economy.
"That was achieved in the protocol, that's what must be delivered upon and any attempt by the British Government to circumvent that, to try to override that is not acceptable to the EU side and certainly shouldn't be acceptable to the Irish Government."
Speaking during Prime Minister's Questions in the Commons on Wednesday, Boris Johnson was asked whether he felt and his colleagues were "above the law".
Mr Johnson replied: "This UK Internal Market Bill is about protecting jobs, protecting growth, ensuring the fluidity and safety of our UK internal market and prosperity throughout the UK and it should be welcomed, I believe, in Scotland, in Northern Ireland, in Wales and throughout the whole country."
When questioned further on his Brexit strategy by former Liberal Democrat minister Alistair Carmichael, the Prime Minister stated: "My job is to uphold the integrity of the UK but also to protect the Northern Irish peace process and the Good Friday Agreement.
"To do that we need a legal safety net to protect our country against extreme or irrational interpretations of the protocol, which could lead to a border down the Irish Sea in a way that I believe - and I think members around the House believe - would be prejudicial to the interests of the Good Friday Agreement and prejudicial to the interests of peace in our country.
"That has to be our priority."