A climate change bill will make the UK government's long-term goal of a 60% reduction in carbon dioxide emissions by 2050 a legally binding target.
The bill does not refer to annual targets
The bill, outlined in the Queen's Speech, will also establish a "Carbon Committee" to ensure the target is met.
But it makes no reference to annual CO2 reductions targets, which opposition parties and environmentalists deem necessary to tackle global warming.
However, ministers said that they would "consider appropriate interim targets".
Announcing the government's planned legislation for the forthcoming parliamentary session, the Queen told MPs and peers: "My government will publish a bill on climate change as part of its policy to protect the environment, consistent with the need to secure long-term energy supplies."
The legislation will be centred around "four pillars":
- placing the target to cut CO2 emissions by 60% from 1990 levels by 2050 on to the statute books
- establishing an independent "Carbon Committee" to work with ministers to deliver reductions "over time and across the economy"
- creating new powers to ensure the 2050 target is achieved
- improving the way CO2 reductions are monitored and reported, including to Parliament
Conservative Party leader David Cameron, speaking in the Commons afterwards, said he was delighted to hear the proposals in the Queen's Speech.
"I hope it will be a proper bill and not a watered down bill. Government has got to give a lead by setting a proper framework.
"That must mean an independent body with annual targets and an annual report from government on its progress," Mr Cameron told MPs.
The prime minister responded by saying that the legislation was likely to include interim targets, but rejected calls for a legally binding yearly goal.
He added that the UK was set to lose about 15% of its electricity generation capacity as existing nuclear power plants reached the end of their operating lives.
"We need to put nuclear power back on the agenda and at least replace the nuclear energy we will lose," Mr Blair declared.
"Without it, we will not be able to meet either our objectives on climate change or our objectives on energy security."
Elsewhere, the proposed bill has been welcomed by environmentalists, who had long campaigned for such legislation.
Friends of the Earth director Tony Juniper said: "The bill is a crucial first step in ensuring the UK plays its part in keeping temperatures below danger levels.
"The next step is to ensure the bill delivers the cuts that are needed through the introduction of annual targets for reducing the UK's carbon dioxide emissions," he added.
The group wants a year-on-year cut of 3% in CO2 emissions; a demand that has been supported by the main opposition parties and 412 MPs.
A spokeswoman for Friends of the Earth said this would deliver a 76% cut by 2050.
The Green Party described the government's proposals as "toothless".
The party's principal speaker, Sian Berry, said: "If we are to to make real headway on curbing our emissions we need to act now - we do not have time for yet more commissions and reviews, for more political delay."
She called for greenhouse gases to be cut by 90% by 2030, and annual reductions of 6%.
But Ian Kearns, deputy director of the left-leaning think-tank IPPR, disagreed: "Calls from some quarters for annual targets are unrealistic in policy terms.
"Targets should be based on a five year cycle that would match the electoral system and would allow the public to hold politicians to account on this crucial issue," he suggested.
Dr Jim Watson, deputy leader of Tyndall Climate Change And Energy Programme, welcomed the move to place the long-term reduction goal on to the statute books. But he also added that more was needed.
"The bill should enable the new Carbon Committee to set interim targets with penalties if these are not met," Dr Watson said.
"Much stronger policies to help businesses and citizens to reduce their emissions are also required.
"In the absence of these vital elements to ensure that we stay on track, there is a risk that the UK will lose the influence it currently has within international negotiations," he warned.
The UK is currently committed to cutting its carbon emissions by 12.5% from 1990 levels by 2012 under the Kyoto Protocol, a legally binding international agreement.
However, there is still no agreement among nations involved in the global accord about what measures should be used when the current phase ends in six years.
Last month, Sir Nicholas Stern, former chief economist at the World Bank, presented the findings of his government-commissioned review on the economics of climate change.
He concluded that the world had to act now on climate change or risk facing devastating economic consequences.
Government officals said it hoped the announcement of the proposed legislation in the Queen's Speech would stimulate a debate among the public and within Parliament about the contents of the bill.
Ministers are expected to publish an Energy White Paper in March 2007.