By Charles MaggsFollow @charlesmaggs
George Osborne is being criticised by green campaigners after reportedly labelling them "the environmental Taliban".
Friends of the Earth have written to the chancellor asking him to explain exactly who he was comparing to the Afghan extremists.
"If the story is accurate, please could you be specific about which individuals, MPs, ministers or organisations you are likening to the Taliban," the letter read.
It comes the day after environment secretary Ed Davey made a speech to the Confederation of British Industry (CBI) where he pushed for clearer targets for carbon emissions and more renewable energy.
Friends of the Earth had already reacted to the speech, saying the Liberal Democrats needed to be more forceful in standing up to the "reckless chancellor".
"We need a clean energy revolution to create thousands of new jobs, tackle climate change and help give us an energy system we can all afford," said chief executive Andy Atkins.
Davey used his speech to spell out how he hopes to increase investment in green technologies through the upcoming growth and industries bill.
"Low carbon is a fast growing sector, where we know there are shovel-ready projects ready to create jobs and inject investment into local economies up and down the UK," he said.
"This vital infrastructure will power our economy and keep energy affordable for decades to come."
He also hinted at setting a carbon target for the future which could allay campaigners' fears.
"A strong case has been made by many investors in energy infrastructure for a decarbonisation target range for the power sector," he said.
"Such a range would make clear our continued commitment to our climate goals".