The pledge by Labour Party leader Jeremy Corbyn to keep Britain in Europe’s nuclear agency post Brexit has been welcomed by the Nuclear Industry Association.

In a speech in Coventry, described as a high stakes showdown with Prime Minister Theresa May, Mr Corbyn said his party would rather contribute to the EU budget to remain part of Euratom than pay more to duplicate its function in the UK.

The Government has said that Britain will withdraw from Euratom when Britain leaves the EU in March next year and transition to new arrangements to cover nuclear safety and standards, including the movement of nuclear materials.

But opponents say the move – which the Government says is needed because the agency sits within the jurisdiction of the European Court of Justice – has the potential to hurt the UK’s nuclear sector, the vast majority of which is based at Sellafield and along Cumbria’s west coast.

Commenting on Mr Corbyn’s statement, NIA chief executive Tom Greatrex said remaining a member of Euratom after Brexit was the “preferred option” of UK’s civil nuclear industry because it offered “continuity and predictability in an otherwise uncertain environment for the UK”.

“The government’s position to replicate the current Euratom arrangements has already proved to be both a time-consuming and uncertain process, and it has only just begun,” he said.

“As yet, no new Nuclear Co-operation Agreements (NCAs) have been signed, discussions for a new trading arrangement with the EU have not begun, an agreement on continued involvement in nuclear research and development has not yet been reached and without a transitional period and continued relationship with Euratom, a new safeguarding inspections regime will need to both be agreed and capable of implementation by March 2019 – something the Office of Nuclear Regulation has stated it would not be able to deliver.”

Barrow and Furness MP, John Woodcock has been a long-standing critic of the move, along with the union Unite. Opponents have questioned the move at a time when Britain is looking to develop new nuclear power stations, including Moorside in West Cumbria and has re-started the process of finding a site for a Deep Geological Disposal Facility to deal with Britain’s most hazardous nuclear waste.

Mr Corbyn’s comments on Euratom were made in a wider speech which set out the Labour Party’s approach to Brexit.

He said he would progress a “new and comprehensive" UK-EU customs union to ensure tariff-free trade after Brexit – a direct challenge to Mrs May, who wants to be outside any customs union so Britain can sign free trade deals with countries around the world after leaving.

Mr Corbyn said free movement of people would end but that EU workers with skills needed by the UK to support public services, such as the NHS, would be actively encouraged to migrate.