Boris Johnson has said he would find it “very difficult” to vote for Rishi Sunak’s new Brexit deal on Northern Ireland, claiming it is “not about taking back control”.

The former prime minister, speaking for the first time on the new arrangements that replace his Northern Ireland Protocol, said the new Windsor Framework still means having to follow EU laws.

“I’m going to find it very difficult to vote for something like this myself because I believe that we should have done something different. No matter how much plaster came off the ceiling in Brussels,” he said.

Mr Johnson said he hopes the new deal works but if it doesn’t, the government should have “the guts” to table his controversial Northern Ireland Protocol Bill – which would allow the UK to rip up part of his Brexit agreement without the EU’s permission.

Brussels argued this would breach international law but Mr Johnson insisted the threat of this action “is what brought the EU to negotiate seriously”.

Speaking at the Global Soft Power Summit, the now backbench MP conceded he made mistakes in signing his Northern Ireland Protocol that caused the DUP to walk out of powersharing because of trade barriers in the Irish Sea.

“I thought those checks would not be onerous since there isn’t that much stuff that falls into that category; most of the goods stay in Northern Ireland,” he said.

Muttering, the former prime minister added: “It’s all my fault, I fully accept responsibility.”

Raising concerns about Mr Sunak’s deal he said: “I’m conscious I’m not going to be thanked for saying this, but I think it is my job to do so: we must be clear about what is really going on here,” he said.

“This is not about the UK taking back control, and although there are easements this is really a version of the solution that was being offered last year to Liz Truss when she was foreign secretary.

“This is the EU graciously unbending to allow us to do what we want to do in our own country, not by our laws but by theirs.”