The High Court in London was set next week to hear the latest legal challenge to the proposal for a coking coal mine near the town of Whitehaven, in northwest England.
Deputy Prime Minister Angela Rayner, who now has responsibility for major planning decisions under her housing, communities and local government portfolio, will not defend its approval, according to government sources.
They said government representatives will confirm at the three-day hearing that "an error of law" occurred when former senior minister Michael Gove approved the scheme in December 2022.
The ministry declined to comment, citing "ongoing litigation".
The new stance comes just weeks after the UK Supreme Court stalled a new oil development in southern England after ruling it was given the go-ahead without proper assessment of its impact on greenhouse gas emissions.
The majority decision on June 20 is seen as setting a major new precedent for fossil fuel projects which will affect the UK's ability to reach net zero by its mid-century target.
Friends of the Earth and a local pressure group have waged the years-long legal battle against the planned mine on the edge of the Lake District national park, accusing the previous Conservative government of ignoring its future climate impacts.
"We're delighted the government agrees that planning permission for this destructive, polluting and unnecessary coal mine was unlawfully granted and that it should be quashed," Friends of the Earth' Jamie Peters said Thursday.
"We hope the court agrees, and that the mine is then rejected."
Proponents of the scheme have argued it will spur economic regeneration in a former mining region that has hit on hard times.
West Cumbria Mining (WCM), the company behind the endeavour, has insisted it will bring to market a supposedly "greener" source of coking coal, used for steelmaking.
The firm has claimed it will operate a "world-leading, legally-binding emissions mitigation scheme", aligned with Britain's net-zero commitments.
But critics -- including climate activist Greta Thunberg -- have argued emissions, including the expected release of 17,500 tonnes of methane annually, make the project incompatible with those aims.
