The Prime Minister has urged Angela Merkel to back his plan for the Northern Ireland Protocol to be renegotiated after Brussels ruled out fresh talks.

During a phone call from Chequers (where he is currently self-isolating) Boris Johnson told the outgoing German Chancellor on Thursday that the disruption being caused to Northern Irish businesses by the protocol was not sustainable.

“He urged the Chancellor and the EU collectively to engage in a constructive and detailed discussion on the UK’s proposals,” according to a statement from No 10.

It came after the European Commission president, Ursula von der Leyen rejected Mr Johnson’s plea to renegotiate the deal after speaking with the Prime Minister.

Ms von der Leyen said Brussels will "be creative and flexible" over the Northern Ireland Protocol "but we will not renegotiate". Ms von der Leyen said Mr Johnson "called to present" the proposals to solve the post-Brexit trade issues between Northern Ireland and Great Britain.

"The EU will continue to be creative and flexible within the Protocol framework. But we will not renegotiate," she tweeted.

"We must jointly ensure stability and predictability in Northern Ireland."

Downing Street said Mr Johnson "set out that the way the protocol was currently operating was unsustainable" during the call. "Solutions could not be found through the existing mechanisms of the protocol," a No 10 statement said.

In further condemnation from Brussels, German MEP David Mcallister, who chairs the European Parliament’s UK Coordination Group, said: "The protocol cannot be renegotiated. It was painstakingly negotiated under high political pressure, ensuring to minimise disruption and to help local communities and businesses."

Earlier this week, the British Government outlined a plan to overhaul the Northern Ireland Protocol, the part of the Brexit deal which set out trade agreements aimed at keeping an open border on the island of Ireland.

Brexit minister Lord Frost proposed a number of measures including ending the European Court of Justice’s control of the arbitration of the deal.

Instead, Boris Johnson’s Government wants a more independent arbitration panel, fearing that the ECJ will make rulings which favour Brussels rather than London.

Ministers also want goods, such as medicines, which are approved for sale in the UK but not in the EU, to be available in Northern Ireland and are lobbying for Brussels to indefinitely delay customs checks which are due to come into effect in Northern Ireland later this year.

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Lord Frost refrained from immediately suspending parts of the deal, despite claiming the UK had cause to do so.

Business Secretary Kwasi Kwarteng told Sky News the protocol was never "something that was going to last forever".

"Nobody thought the Northern Ireland Protocol was going to define the role of Northern Ireland within the UK forevermore, it was something that was flexible. When people say they’re not going to look at the protocol again, I say ‘well, let’s just see’,” he said.

The difficulties caused by the arrangements have meant Northern Ireland had faced reductions in supermarket product lines.

Marks & Spencer’s chairman warned there will be some "gaps on shelves" in Northern Ireland this Christmas.

One idea put forward would be for UK traders to declare whether the final destination for their goods was Northern Ireland or the Republic.

Lord Frost’s proposals are thought to require changes to at least three of the protocol’s articles.