The California-based firm pointed to high energy costs and regulatory uncertainty for its decision to pause its Stargate UK project.

Stargate UK was announced in September last year as part of a combined £31 billion investment in Britain by US tech firms.

The announcement of the investment, as well as a UK-US tech prosperity deal, was made during US President Donald Trump’s state visit to Britain.

Stargate UK is a data centre planned for the North East in partnership with British firm Nscale.

The delay to the project is a huge blow to Prime Minister Keir Starmer’s bid to turn the UK into “one of the great AI superpowers”, as Labour scrambles for economic growth.

The Tories heaped blame on the “Net Zero” agenda of Mr Miliband, the Energy Secretary, for harming Britain’s AI ambitions.

Senior Conservative MP Andrew Griffith, the Shadow Business Secretary, said: “Ed Miliband’s suicidal energy policy has just cost us another huge investment.”

Griffith added: “The UK has top AI talent and labs but huge energy costs because of Labour’s mad Net Zero agenda.

“If Labour let us fall behind on AI, British businesses will lose out to competitors.”

Mel Stride, the Shadow Chancellor, said OpenAI’s decision was a “damning verdict” on Chancellor Rachel Reeves’ “economic mismanagement”.

“Britain should be leading the AI revolution”, Sir Mel said.

“Instead, Labour are delivering high costs and lost opportunity.

“The message to investors is clear: under Keir Starmer, Britain isn’t open for business.

“We need cheaper energy, smarter regulation, and a Government that actually understands how to attract jobs and investment.”

Ofgem, the energy regulator, recently warned that vast data centres needed for AI systems will require more energy than is currently used by the whole country.

It revealed that a “significant portion” of projects in the queue for connections to the UK’s electricity grid are data centres.