A class action has been launched against the Government claiming post-Brexit Irish Sea trading arrangements infringe the economic rights of Northern Ireland citizens.

If successful, the commercial litigation could pave the way for companies adversely affected by the terms of the Northern Ireland Protocol to claim significant financial damages from the Government.

The legal move is different to separate legal challenges that have been mounted against the Protocol on constitutional grounds.

The action, which names the Cabinet Office and Attorney General as defendants, seeks a declaration from the High Court in London that the provisions in EU Withdrawal Act relating to the Protocol conflict with the economic rights provided for in the UK Human Rights Act.

The 1998 Human Rights Act enshrines the European Convention on Human Rights in domestic legislation.

The claim form lodged with the High Court this week names Ballymena haulage company Blair International and DUP North Antrim MP Ian Paisley as the initial claimants.

Solicitor Clive Thorne, who is acting for the claimants, said the next legal stage move would be to formally add a “long queue” of interested companies to the action. A court hearing would then follow, said Mr Thorne.

“We’re in touch with a whole series of other claimants who it is envisaged will join the action,” the lawyer told the PA news agency.

The Northern Ireland Protocol was agreed by the EU and UK during the withdrawal negotiations in an effort to prevent a hard border on the island of Ireland.

It achieves that by moving many regulatory and customs processes to the Irish Sea, with goods arriving into the region from GB subjected to significant new red tape.

The arrangements have caused some disruption to trade since the start of the year as firms have struggled with the extra bureaucracy.

Unionists and loyalists are vehemently opposed to the arrangements, claiming they undermine Northern Ireland’s place in the UK internal market.

Mr Thorne said the claim argues that the Protocol discriminates against businesses involved in GB/NI trade, hindering their ability to operate as effectively as UK traders not involved in Irish Sea shipping.

Mr Thorne, a partner in London-based law firm McCarthy Denning, said those economically harmed included Northern Ireland businesses but also GB traders who did business in the region.

He said the second aspect of the action centred on the contention that there was no democratic mandate for the Protocol within Northern Ireland

“We would say that the Protocol legislation is unlawful because it conflicts with the rights under the Human Rights Act and contained in the European Convention,” he said.

The solicitor added: “This very much is a piece of commercial litigation, rather than political or constitutional litigation, whereby businesses in Northern Ireland, and also in Great Britain, have suffered adversity as a result of the framing of the Protocol and the way in which it has become part of United Kingdom law.”

Potentially I think this will end up being a multi-million pound legal claim on behalf of several companies for loss against the Government.

Mr Thorne said compensation claims would likely follow if the High Court declared the Protocol unlawful.

“If the Government is found to have acted unlawfully, then it has opened the door to possible subsequent claims for compensation for the damage suffered,” he said.

A separate legal challenge involving former Brexit MEP Ben Habib and Baroness Kate Hoey, and supported by the leaders of the three main unionist parties in Northern Ireland, is challenging the Protocol on constitutional grounds, claiming it undermines the Act of Union and the terms of the region’s historic Good Friday peace deal.

Mr Paisley said the new legal challenge complemented the constitutional judicial review.

He added: “It’s very much looking at the commercial damage that’s being done to various commercial interests and the various sectors within the economy and it has to attack the Protocol from that point of view, so that’s why it’s different but it’s very complementary.

“I think it is important that as many people come together and demonstrate to the Government that this has to be challenged constitutionally, politically, societally and economically.”

Mr Paisley said using his name as a claimant was a “technical” move. He said his main role was to provide a pathway to encourage and facilitate companies to join the challenge.

“Potentially I think this will end up being a multimillion-pound legal claim on behalf of several companies for loss against the Government,” he said.