Tony Blair was under intense pressure last night to commit the Government to statutory annual targets for cutting harmful CO2 emissions as part of the first legislation specifically aimed at combating climate change.

Environmental groups and MPs from all parties united to increase their demands on the Prime Minister to outline bold action in the Government's forthcoming climate Bill. Campaigners warned ministers against producing a "toothless" and "watered down" Bill.

Mr Blair has made climate change one of the key priorities of his nine years in office, but he was facing humiliating criticism from all sides for being too weak to promise tougher action. David Cameron, the Tory leader, stole a march on Mr Blair by publishing his own climate change Bill after the Prime Minister refused to make any commitment when he was challenged in the Commons.

The Conservative climate change Bill would force the Government to produce an annual target for reducing CO2 emissions and create an independent climate change commission to check on progress on cutting carbon dioxide emissions. The Environment Secretary would be required to seek approval for an annual carbon budget report to Parliament.

David Miliband, the Environment Secretary, is understood to have won a Whitehall battle to secure a slot for a climate change Bill in the package of legislation to be announced on 15 November in the Queen's Speech. But it is likely to fall far short of demands for annual targets by environmental groups and MPs.

Downing Street confirmed yesterday that the Government favours long-term targets rather than annual targets. "We think we should have long-term targets because we can work towards those in stages," said the Prime Minister's official spokesman.

One minister who has worked on the strategy said: "We think we can get better results if we set long-term targets. Annual targets can have negative effects, if we don't meet them. But long-term targets encourage people to try harder." These excuses were dismissed by environmental groups.

Tony Juniper, the executive director of Friends of the Earth, said 10-year targets were "just not good enough. Long-term targets have failed to deliver in the past and they will fail again. A commitment to legally binding, year-on-year cuts is needed if we are to ensure that every government does its bit to cut emissions."