Green MP Caroline Lucas has accused the government of lacking ambition on the prevention of climate change.
During a general debate on energy efficiency on 30 June 2010, the MP for Brighton Pavilion said: "The government has said it wants to be the greenest government - unfortunately, that's not a very ambitious target.
"But nonetheless, if they do want to do that, they're going to have to do a lot better," she warned.
Winding up the debate, shadow energy minister Emily Thornberry said the government had a "very difficult" job on energy.
"What about the fuel poor? And will you really be cutting carbon? If you do, you will have our support. Otherwise you will not," she said, speaking from the despatch box for the first time.
Energy Minister Charles Hendry told Ms Lucas that she should continue to "harry the government... to chase us to do better".
"We are most determined to be the greenest government there has ever been. But I want us to know we will be challenged truly by people who always want to raise the bar higher," he said.
The debate ended without a vote.
Part one of the debate can be found