Reports that David Cameron told aides to "get rid of the green crap" from the government's programme may have been denied, but they clearly hit a very raw nerve in the Liberal Democrat party.

Cameron's coalition allies are already concerned at the prime minister's apparent cooling on green issues after the row over energy prices saw him pledging to remove environmental levies from consumers' bills.

So there is an unspoken suspicion that, even if Cameron didn't use the words reported, they nonetheless represent his current thinking.

The clearest sign of that suspicion and irritation came from LibDem Treasury secretary Danny Alexander who snapped: "Anyone who thinks we should get rid of that is full of crap."

Deputy prime minister Nick Clegg appeared equally sensitive when questioned about green issues on his weekly radio phone-in show. He told a caller: "It isn't all crap, of course.

"It is worth remembering that a lot of the policies we've got support tens of thousands of people who work in the booming green energy sector, actually keep bills down in the long run."

The LibDem hackles were raised by reports in two national newspapers. One claimed that a senior Tory source had said: "He [Cameron] is telling everyone, 'We've got to get rid of all this green crap'. He's absolutely focused on it."

The prime minister, however, dismissed the suggestion with his spokesman telling reporters that he had never heard the prime minister use such a term.

"The position on rolling back the cost of levies is that which the prime minister has set out several times in PMQs," he said.

"This is a government that has set up the first-ever green investment bank, that has commissioned the first nuclear power station since 1995, that is spending £2bn on flood defences."

The prime minister still believed his was the greenest government ever, the spokesman added.

There is an ongoing rift between Cameron and the LibDems after he made the surprise announcement he was planning to remove green levies from energy bills as a way of combatting Labour's energy freeze policy.

Clegg had been given only 30 minutes' notice of the policy and later squeezed a concession from Cameron that the levies would be moved to general taxation instead. The announcement is expected in next months autumn statement.

But it has increased suspicion amongst Liberal Democrats that the Tories are not as committed to the green agenda as they once were.