David Cameron said the government should adopt his ideas

Launching a campaign for annual binding targets on cutting carbon emissions, Tory leader David Cameron said it was vital any bill was not "watered down".

But Prime Minister Tony Blair would not comment on next month's speech, and said annual targets would be "very, very difficult to deliver".

The UK is thought unlikely to hit its target to cut emissions by 20% by 2010.

But a government report found earlier this year it could reach a reduction of 15 to 18% by then.

Targets 'needed'

Mr Cameron said binding annual targets were necessary "otherwise there would be no prospect of hitting the 2050 target".

He also wants an independent climate change commission, so it can monitor whether targets are being met.

Mr Cameron challenged Mr Blair and Environment Secretary David Miliband to "take on these ideas" for a bill, but added that it was vital they were not watered down.

If any secretary of state failed to meet targets two years in a row, then that would be embarrassing and there would be questions to answer Peter Ainsworth Shadow environment secretary

His bill, two pages printed on recycled paper, did not have details about what would happen if targets were not met.

Shadow environment secretary Peter Ainsworth said: "There are no overt sanctions, but if any secretary of state failed to meet targets two years in a row, then that would be embarrassing and there would be questions to answer."

In the Commons, Mr Blair said there had been "huge investment in renewable energy and energy efficiency.

"And the Climate Change Levy - which has reduced dramatically what would otherwise have been the carbon dioxide and greenhouse emissions - is absolutely vital, but it must also be practical and workable."

He also said Britain would be one of the few countries to meet targets under the Kyoto treaty.

The Kyoto treaty commits Britain to keeping annual greenhouse emissions during the period 2008-2012 to 12.5% below 1990 levels.

In 2002, the UK was 14.4% below 1990 levels, and in 2003, 13.4% below.