Regulations introduced by the UK Government represent “another piece of the Irish Sea border superstructure”, DUP peers have warned.

Accusations that legislative orders made by ministers confirmed “the splitting” of Northern Ireland from the British mainland came amid demands by the DUP for the London administration to address concerns over post-Brexit trading arrangements for the region.

The largest unionist party withdrew from the devolved institutions at the start of last year in protest at the Northern Ireland Protocol.

While the UK and EU agreed a revamped deal with the Windsor Framework, the DUP has insisted it will not return to powersharing at Stormont until the Government provides further assurances over Northern Ireland’s place in the UK internal market.

There has been renewed criticism after the Government brought in measures to implement the revised arrangements, specifically a green lane for the movement of goods.

As well as concerns over the speed with which they were introduced and the lack of consultation, the DUP argued they still failed to secure the promised “unfettered trade” between Northern Ireland and Great Britain.

Speaking in Parliament, former DUP deputy leader Lord Dodds of Duncairn said: “Make no mistake, the regulations before the House… along with others, establish a regulatory and customs border in the Irish Sea, with Northern Ireland subject to EU jurisdiction in over 300 areas fundamental to our economy.

“These regulations do not do what the Government claim they do. They are in fact another piece of the Irish Sea border superstructure under the Windsor Framework protocol.”

He added: “You cannot expect unionists to operate a regime that ruptures the union.”

Lord Dodds went on: “The Government know what they need to do. If they seriously believe in devolution, if they seriously believe in the agreements that they have entered into previously, and if they seriously value the union, as we are told they do, then they will legislate for the necessary change – real, effectual change.

“It is really up to the Government as to what happens next.”

Fellow DUP peer Lord Morrow said: “Contrary to Government statements that the Windsor Framework provided unfettered access to and from Northern Ireland within the United Kingdom internal market, these regulations affirm an arrangement that actually accepts an ongoing border in the Irish Sea.

“These regulations are of immense political and constitutional importance because they affirm the splitting of our country into two.”

He added; “All is not well and is not going to get better until the Government grasps the situation.”

Former Labour MP Baroness Hoey, a Brexit supporter who now sits as a non-affiliated peer, said: “Northern Ireland has been taken away from the United Kingdom.”

DUP peer Lord McCrea of Magherafelt and Cookstown said: “I know that some within government have expressed extreme frustration with the DUP, for they claim that they have provided sufficient fig leaves for the DUP leader to get back into Stormont.

“I find that statement from a Government minister deeply insulting. Surely everyone knows that fig leaves were not able to cover Adam and Eve in the garden, and they will not be able to cover any grubby deal done by the Government over the heads of the people of Northern Ireland when it deals with the constitutional future of our children and the generations to come.”

Labour frontbencher Baroness Anderson of Stoke-on-Trent said: “We consider this legislation to be vital to the implementation of the Windsor Framework.

“While the Labour Party doesn’t believe the Windsor Framework is perfect we do believe it is a substantial improvement on what came before.”

Responding, Environment Minister Lord Benyon said: “The Windsor Framework restores the smooth flow of trade within the UK internal market by removing the unnecessary burdens that had disrupted east-west trade.

“We are confident that the Windsor Framework upholds our objectives to ensure that Northern Ireland’s place in the union is protected.

“Specifically, the framework allows for goods which meet British standards to be available in all parts of the UK, ensuring that consumers in Northern Ireland have access to the same goods as those elsewhere in the UK.”