Exclusive: Friends of the Earth tells Keir Starmer any major green cuts by Rachel Reeves will be challenged

If the decisions the UK government makes in its upcoming spending review are not in line with the net zero climate target it risks being taken to court again, campaigners have said.

Rachel Reeves, the chancellor, will set out her spending review for the rest of this parliament on Wednesday. Amid continuing economic uncertainty and Labour’s promise to boost defence spending, many departments are facing deep cuts to dearly held commitments.

Ed Miliband, the energy secretary, has been fighting for the promised £13.2bn for home insulation to be protected, as experts and charities have warned that failing to insulate Britain’s draughty homes will undermine the restoration of winter fuel payments to many pensioners. There are also questions over the funds available for GB Energy, the publicly owned company that invests in green energy, and support for farming and for flood defences.

The campaign group Friends of the Earth, which successfully took the last Conservative government to court over its net zero plans, has said it will take legal action again if Reeves’s plans appear to fall short.