BORIS Johnson’s threats to rewrite part of the Brexit deal he signed would result in retaliation from Brussels, the EU's ambassador in the UK said.

Joao Vale de Almeida said there was no scope for reopening negotiations on the Northern Ireland Protocol and warned that “action calls for reaction” if the UK did go down the route of tearing up parts of the deal.

Foreign Secretary Liz Truss has set out plans for legislation to amend the protocol to address concerns about the implementation of the deal.

The Prime Minister has insisted of his plans for the protocol, “we don’t want to nix it, we want to fix it”.

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But the ambassador said: “It’s not very reassuring if you go into a negotiation where you are presented with two options – either renegotiation or unilateral action to override the treaty.

“This is not the best way to fix, this is rather a way maybe to nix.

“So if we want to fix it, which is what we want and I understand this is what the Government wants as well, we need to create a better atmosphere.”

There was “untapped potential” in the proposals set out by European Commission vice president Maros Sefcovic in talks with the UK Government, he said, warning of retaliation if the UK instead chose to act unilaterally.

“There is still potential in the proposals that we’ve made, we would like to focus on that instead of going unilateral,” he said.

“Unilateral calls for unilateral. Action calls for reaction.

“And is that what we want, an escalation around Northern Ireland at this present point in time? I don’t think so.”

The ambassador told reporters in Westminster there was little prospect of the EU’s member states giving Sefcovic a mandate to rewrite the protocol in his talks with Truss.

“We were told that we should get a new mandate but I can tell you very clearly what the member states are telling us is very simple: You don’t need a mandate and even if you ask for one, you will not get it.”

READ MORE: UK will table bill to scrap parts of Northern Ireland Protocol in 'weeks' says Liz Truss

He said there was a lack of trust between the two sides and there was little sign of a “happy ending” in the protocol saga.

“I’m worried by the low levels of trust that exist today between the EU and the UK, between our leaders, between all of us that are involved in this relationship,” he said.

He compared the protocol rows to a long-running drama: “I was hoping to see in this season of this saga … more creativity and hopefully a happy ending. I’m not seeing it for the moment and this is an area where I think things have not changed enough.”

Co-operation on issues such as the war in Ukraine and climate change showed how the two sides could work together.

But the ambassador said: “If I look at the wider picture of our relationship, our problems with the Northern Ireland Protocol have an excessively negative impact on the quality of our overall relationship and we need to overcome this situation.”