THE NORTH'S dual market access is "in danger of unravelling" if the Stormont brake becomes a mandatory veto, it was claimed last night.

Secretary of State Chris Heaton-Harris said on Thursday that the British government would be "bound" to block any new EU law if enough MLAs supported the move.

The Stormont brake element of the Windsor Framework is a mechanism similar to assembly's petition of concern that would enable 30 MLAs from two parties to raise concerns about new EU rules, stalling their implementation.

However, there appear to be differing interpretations of how the brake would work, along with concern that it could hand a veto to a minority of MLAs.

Pressed on whether the government was bound to veto a law if the brake was pulled, Mr Heaton-Harris said: "So the criteria really have to be fulfilled at the assembly level, and yeah, we make an assessment, but in the piece of secondary legislation that we'll be bringing forward, the government will be bound, yeah."

Chris Heaton Harris rewriting Stormont brake rules saying if it is pulled (presumably by 30/90 MLAs) the EU legislation would be “disapplied immediately and goes to the EU-UK Joint Committee where the UK would be bound to veto”. What about safeguards blocking trivial objections? pic.twitter.com/YdbGBJBS2Z

— Irish Agreement (@irishagreement) March 9, 2023

He said that technical talks on the mechanism had been held with the Stormont political parties.

The Northern Ireland Office has declined to elaborate on what Mr Heaton-Harris said.

However Taoiseach Leo Varadkar said the UK would be required to engage with the EU to resolve any issues around the bloc's laws being introduced in the north.

"I think what we're going to have to see is the legislation that the British government introduces, and they've committed to consulting with the five main parties in Northern Ireland on that and also the Irish government," said Mr Varadkar.

"We see the Stormont brake as a red flag mechanism, a mechanism by which 30 assembly members from two parties or more can raise an issue, an issue that we will then try to sort out between the EU and UK and that if things can't be resolved we then go to international binding arbitrations, that's how we would see it develop, that's certainly how it's written down in the legal text that was agreed between the EU and the UK.

"But of course the UK can bring in its own internal legislation, but they have committed to consulting with the parties on that."

Alliance deputy leader Stephen Farry said the the secretary of state and British government were "sending mixed messages" about how the brake would be applied.

"We understand it is to be used sparingly and with a high bar to proceeding – there are major pitfalls in selling the Windsor Framework on false pretences," he told The Irish News.

"By contrast if the UK government proceed with a mechanism that is at odds with what has been agreed and we see regular vetoes deployed, then Northern Ireland's dual market access is in danger of unravelling."

SDLP MP Claire Hanna said she welcomed a role for Stormont in "anticipating and addressing any challenges that may come from new law or divergence".

"But we have been clear with the UK government that politics here doesn’t lead another layer of dysfunction and that our pitch to investors about the trading rules has to be certain and clear," she said.

A Sinn Féin spokesperson said: "We are consulting senior assembly officials on the Stormont brake about how it would apply in practice and its implications.

"However, my understanding is that it is a mechanism of last resort to be used only in exceptional circumstances if at all."