Gavin Robinson has said his party used the Stormont Brake mechanism “legitimately” and “the opportunity will present itself” to do so again in the future.
The DUP leader had earlier stated the British government had made a “grave mistake” in refusing to activate the Stormont brake over updated EU laws on the labelling of chemical products.
He claimed the amended regulations, which will apply in Northern Ireland, would result in increased costs for manufacturers in the north and new barriers to trade.
But First Minister Michelle O’Neill, said it was now time for politicians to “make things work” in relation to post-Brexit trading issues.
Secretary of State Hilary Benn announced on Monday that the brake, an element of the Windsor Framework, would not be pulled over the amended EU rules.
Unionist parties at Stormont had backed a DUP motion in December, requesting the British government activate the brake, which could have seen it preventing the amended law from applying in Northern Ireland.
But Mr Benn concluded the tests for utilising it had not been met.
Mr Robinson said: “The government’s decision not to activate the Stormont brake on this important issue is wrong.
“The secretary of state’s decision to ignore publicly presented evidence from industry representatives about the updated EU law on chemical labelling is a grave mistake that will exacerbate trade friction between Great Britain and Northern Ireland.”
He added that it was time the UK government started “standing up for Northern Ireland”.
On Monday evening, he said the government “could have gone further” but as a result of the DUP attempting to pull the Brake they are “now taking steps to ensure the integrity of the UK internal market”.
He told the PA News Agency: “We’ve used this process legitimately. It has kick-started the government into a process that will ensure we don’t see divergence. Have they used the policy or the proposals to the full extent? No, they have not, and I’m not entirely surprised.”
Mr Robinson further stated: “There’s not a question of us walking away from Stormont over this issue. Should the government have used the powers to their full extent? Yes, they should.
“Did the use of this process change their position and the provision of greater information and the commitment that there won’t be a divergence. Well, yes, it has. That is good news.”
The DUP leader also said: “There will be issues that come up on a weekly and monthly basis where the opportunity will present itself to use this mechanism again.”
When asked about the decision at the Stormont Assembly, Ms O’Neill said politicians had to find “pragmatic and reasonable” ways to deal with issues as they arose.
She said: “The secretary of state has made his call in terms of the Stormont brake.
“We just need to find ways to make things work.”
Ms O’Neill said uncertainty over post-Brexit trading issues arose because Northern Ireland had been “taken out of Europe against our wishes”.
She added: “We have to deal with the consequences in a post-Brexit world.”
Alliance Party deputy leader Eoin Tennyson said the Stormont brake should only be wielded in “exceptional circumstances”.
He said: “Where there are issues arising from an EU regulation, this should be addressed at the earliest possible opportunity through engagement between the UK government and the European Commission.
“Ultimately, it is only through closer alignment and co-operation between the UK and the EU that the impact of Brexit will be mitigated.”
Ulster Unionist MLA Steve Ailken said the Stormont brake had “demonstrably failed at this first hurdle”.
He added: “A careful examination of the regulation, coupled with the cumulative impact of multiple changes now being imposed, shows that this is creating increasing and significant divergence from our largest market, our own country.
“That this is the case should be readily apparent to the Secretary of State, if he just bothered to look.”
SDLP Stormont leader Matthew O’Toole said the brake was a “distraction from real issues”.
He said: “Instead of continual debate around the Stormont brake, we need the Secretary of State and the UK government to engage with the EU around a permanent solution that recognises Northern Ireland’s unique position and allows us to make the most of dual market access.”
TUV leader Jim Allister said the government’s decision not to pull the Stormont brake should “break Stormont”.
He described the decision as a “calculated slap in the face of all democrats”.
