The leader of the DUP has endorsed the Prime Minister’s Brexit proposals as a “serious and sensible way forward”.

Arlene Foster said the ability for the Stormont Assembly to opt in and out of the tabled all-Ireland regulatory arrangements was the “big difference” from the previous withdrawal deal.

Political rivals have accused the DUP of backing down on its vehement opposition to any agreement that resulted in a new regulatory border between Northern Ireland and the rest of the UK.

The party leader, arriving back in Belfast after attending the Conservative Party conference in Manchester, insisted the beefed-up role for Stormont provided the democratic accountability she desired.

Ms Foster also welcomed Boris Johnson’s pledge for an accompanying new economic package for Northern Ireland, but insisted that was not the only reason her party was supporting his Brexit plan.

“We believe this is a serious and sensible way forward to have engagement with the European Union in a way that allows us all in the United Kingdom to leave the European Union, therefore we will be supporting this plan,” she said.

“What it does is allows us to leave the European Union customs union, it allows us to leave the single market and then we opt in if we are not in the position to put in alternative arrangements at that time,” she added.

“So therefore we consent to whatever is coming forward, so that is the difference.

“It is a big difference and we believe it is something that works for Northern Ireland whilst letting us leave the European Union.”

Ms Foster urged Europe to give the plan serious consideration.

“This is a sensible way forward, it is a stable way forward, it allows the people of Northern Ireland a role which they didn’t have, it gives them the consent they didn’t have in terms of the anti-democratic nature of the backstop and I hope people will look at it in a serious way,” she said.

The DUP leader was asked whether the instability at Stormont, which has seen Northern Ireland without a powersharing government for nearly three years, was the plan’s fatal flaw.

“I don’t think it (Stormont) would be inherently unstable if we got back,” she said.

“I think we should be back, we should be there. I am willing and ready to go back into Stormont. I am ready to appoint ministers tomorrow and I hope that the others will see that for many, many reasons we need to be in an Executive and Assembly.”

On Mr Johnson’s proposed new economic deal for Northern Ireland, Ms Foster said: “That’s not just why we support the deal.”

She added: “In terms of the new economic deal I think the Prime Minister recognises that Northern Ireland needs to have more investment in it. I very much welcome that.”

Ms Foster indicated that any decision to opt in or out of the regulatory arrangements would need cross-community support at Stormont.

“Part of the difficulty of this process is people have been talking about Northern Ireland in terms of majorities again and I don’t think that works, I think we need the consent of the unionist people in Northern Ireland and the consent of the nationalist people,” she said.

“That is what the Belfast (Good Friday) Agreement is based on, so if we get back into the Assembly, and I hope we get back into the Assembly and Executive very soon, then we can have those conversations about how we move forward collegiately for Northern Ireland.”