With the environment becoming a central political issue, the Conservative leader challenged the Prime Minister to accept his proposals for annual targets on cutting greenhouse gas emissions, saying that Britain’s climate change goals would not be met without them.

However, in angry exchanges in the House of Commons, Mr Blair ruled out year-on-year targets, declaring that they would be “very, very difficult” to meet.

All the main political parties are committed to reducing emissions of carbon dioxide by 60 per cent before 2050. However, the Government believes that annual targets between now and 2050 are impractical, and that there should instead be targets only every three, five or ten years.

At a press conference to publicise the Conservatives’ eight-part “Bill”, Mr Cameron said: “Unless we have annual targets between now and then there really is no prospect of hitting it.”

The Conservative “Bill” would establish an independent climate change commission to set statutory annual targets and monitor whether they were being reached with an annual report. Mr Cameron said that, without the discipline of yearly targets putting constant pressure on governments: “We’ll have this big target for 2050, we’ll all say warm things about it, and then miss it.”

Challenged on the issue during Prime Minister’s Questions, Mr Blair rejected the proposals, saying: “He is asking for statutory, binding, year-on-year targets, which are very, very difficult to deliver because of the changes that may happen in any one year.”

He said that any measures to tackle climate change have “got to be practical and workable”, and that “such proposals must also be entirely compatible with the interests of business and consumers”.

However, Mr Cameron’s policy won the backing of Friends of the Earth, whose director, Tony Juniper, said: “Long-term targets have failed to deliver in the past, and failed to deliver 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.”

Mr Blair is already under pressure to introduce binding targets from more than 400 MPs who signed a Commons motion, and by a coalition of environment campaigners who have demanded a climate change Bill.

The Conservatives published their “Bill” as part of their strategy of resembling a government-in-waiting, setting the agenda, rather than an Opposition just saying no to everything. Claiming that the Government was repeatedly stealing his policies, Mr Cameron taunted Mr Blair: “If you want to get something to happen in this country, get the Leader of the Opposition to suggest it.”

The Conservative “Bill” would establish an independent climate change commission of scientists, economists and representatives of charities and business. The commission would set annual targets up to 2050, but review them in a four-year rolling programme taking in actual progress.

The commission would report to Parliament four times a year on the progress, as well as produce an annual report — the “carbon budget report”. The Environment Secretary would then be required to set out the Government’s strategy of how it was going to hit the forthcoming targets.

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