Stripping green levies from energy bills would be an "own goal" which could cost jobs and reduce support for poor households, Nick Clegg has warned in the latest sign of division within the Coalition.
But Clegg, who was given little notice of the Prime Minister's surprise announcement, said: "It wasn't something that I was fully expecting and it's not something that I fully agree with."
He did not accept that green levies were the main reason for price hikes, putting 60% of the increase down to rising wholesale costs in the energy market.
Clegg, who also rejected Labour leader Ed Miliband's call for a price freeze as a "con" which would "see prices go up, jobs go down, investment go down", attacked the "new theory emerging on the right of British politics which says it's all the fault of us caring about the environment".
He told the BBC Radio 4 Today programme that he would hold talks with the Prime Minister to find a way forward, which would involve testing the various charges and could see some - such as the warm homes discount worth £135 to two million poor households - moved to general Government spending paid for through taxes.
But he added: "I'm not frankly entirely sure what rolling back green levies, if removing all green levies which help two million people on very low incomes, which help support thousands of jobs in our green renewable energy sector, if that is what is meant I think that would be an own goal."
Setting out the next stages Clegg said the Government would see if its objectives could be "delivered in a more cost-effective way".
He said: "We will stress test all these different levies. If we can deliver those objectives of keeping the lights on, insulating people's homes, helping the fuel poor, supporting our green economy for less - of course I don't want to see an extra penny on people's bills than is actually necessary - that is what we will do, as we always do in the coalition whatever our differences, we resolve them."
Clegg is reported to have only been told about Cameron's decision to announce the plan at Prime Minister's Questions around 30 minutes before the Commons showdown with Miliband, which was dominated by exchanges on energy policy.
The Deputy Prime Minister refused to go into detail of how he heard about the move through his office, saying: "I don't think that's the key thing here. The key thing is what do we do to strike this really difficult balance between getting bills down where we can and keeping the lights on, investing in green jobs and helping the fuel poor."
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