EU leaders have warned the UK Government it will not renegotiate the deal on Northern Ireland’s post-Brexit trading arrangements after Lord Frost demanded "significant change" to the terms.

Brexit Minister Lord Frost said “we cannot go on as we are” but held back – for now – from taking the dramatic step of effectively suspending parts of the deal, even though he claimed the UK would be justified to do so.

Boris Johnson hit out at the “inflexible” approach of the EU in implementing the agreement he signed but said there was an “opportunity to proceed differently”.

But European Commission vice-president Maros Sefcovic flatly rejected the UK’s call to renegotiate elements of the Northern Ireland Protocol.

The protocol, part of the Brexit divorce deal agreed by the UK and Brussels, effectively keeps Northern Ireland in the EU’s single market for goods.

This means checks on goods being sent from Great Britain into the single market – and in some cases could result in prohibitions on certain products that do not comply with EU rules.

The protocol was put in place to ensure there would be no hard border with Ireland, but it has instead effectively placed a trade barrier in the Irish Sea.

READ MORE: UK Government seeking 'significant change' to Northern Ireland Protocol

The Scottish Government’s External Affairs Secretary, Angus Robertson, said the situation was ”the UK Government’s own making” due to “their pursuit of a damaging hard Brexit”. 

He added: “The UK Government is effectively gambling with our EU trade by trying to renegotiate a deal, agreed by both sides and hailed by the Prime Minister at the time as ‘oven-ready’. It is a shambolic situation and one that is totally unnecessary and self–inflicted. 

“We are very concerned that the existing tension between the UK Government and the EU can only be further intensified over this crucial issue in the coming weeks and months and that today’s statement will further erode trust. 

“We urge the UK Government to proceed in a spirit of collaboration, not conflict, with the EU over this crucial issue.” 

Lord Frost said a “new balance” in the arrangements was needed – pointing to economic and social damage.

He told peers: “We urge the EU to look at it with fresh eyes and to work with us to seize this opportunity and to put our relationships on to a better footing. We stand ready to work with them to deliver the brighter future which is in reach.”

The proposals published by the Government include continued access in Northern Ireland to goods from the rest of the UK, through a regulatory approach which accepts both British and European Union standards.

The UK's plans also include an “evidence-based and targeted approach” to goods at risk of entering the single market, but products destined just for Northern Ireland would be allowed to circulate “near-freely”.

Under the plans “full customs formalities would be required for goods going to Ireland and the UK would undertake to enforce them" while "other goods would not require customs processes”.

Lord Frost set out why change was necessary, highlighting the economic and social damage he said would have justified the use of Article 16, effectively tearing up parts of the deal.

“There has been significant disruption to East-West trade, a significant increase in trade on the island of Ireland as companies change supply chains and considerable disruption to everyday lives.

“There has also been societal instability, seen most regrettably with the disorder across Northern Ireland at Easter.”

There was a “false, but raw” perception in the Unionist community of separation from the rest of the UK which has had “profound political consequences”.

Lord Frost told peers there had been progress in talks with the EU – with officials led by Mr Sefcovic – but “overall, those discussions have not got to the heart of the problem”.

“Put very simply, we cannot go on as we are,” he said.

READ MORE: How has leaving the EU impacted Scotland's fishing industry?

But in his response, Mr Sefcovic said: “We will continue to engage with the UK, also on the suggestions made.

“We are ready to continue to seek creative solutions, within the framework of the protocol, in the interest of all communities in Northern Ireland.

“However, we will not agree to a renegotiation of the protocol.”

Irish Foreign Minister Simon Coveney said: “The EU has consistently said it is ready to find flexible, practical approaches to address the difficulties citizens in Northern Ireland are experiencing as regards the implementation of the protocol.

“However, any solutions must take place within the framework of the protocol and the principles that underpin it.”

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

He called for a “standstill” period, preserving the current grace periods and suspending legal action taken by the EU against the UK while changes are negotiated.

The EU was briefed about the proposals in advance and there has also been diplomatic engagement with the US – President Joe Biden, who has Irish ancestry, has warned against anything that could jeopardise the peace process.

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.

Archie Norman told BBC Radio 4’s Today programme: “This Christmas, I can tell you already, we’re having to make decisions to de-list product for Northern Ireland because it’s simply not worth the risk of trying to get it through.”

Angela McGowan, CBI Northern Ireland director, said: “After months of deliberations, businesses are exasperated that the protocol continues to dominate the headlines with no end in sight. ”

Shadow Cabinet Office minister Baroness Chapman said: “The Government promised to get Brexit done. And yet here it is trying to unpick it.

“The Government must find agreement to fix the problems the Prime Minister created.”

DUP leader Sir Jeffrey Donaldson welcomed the Government’s move as a step in the right direction but added: “Sticking plasters and short-term fixes were never going to work. We need a proper renegotiation.”