Blair, who last week returned from a vacation at the home of Bee Gees singer Robin Gibb in Miami, Florida, told Sky News television that it would be "impractical" to expect people to take fewer flights.

"It's like telling people you shouldn't drive anywhere," said Blair. "I personally think these things are a bit impractical actually to expect people to do that."

The British leader, expected to stand down this year after 10 years in office, called for efforts to "make air travel more energy efficient," and to "develop the new fuels that will allow us to burn less energy and emit less.

"How -- for example -- in the new frames for the aircraft, they are far more energy efficient," he said.

Greenpeace campaigner Emily Armistead said Blair was not only deluded but had undermined any claim he had to leading the fight against global warming.

"Tony Blair is crossing his fingers and hoping someone will invent aeroplanes that don't cause climate change. But that's like holding out for cigarettes that don't cause cancer," she added.

"The prime minister should be halting airport expansion and getting people back onto the railways. He's finally forfeited any claim to be a world leader on climate change."

Friends of the Earth head of campaigns Mike Childs said it was "disappointing" Blair had refused to set an example when aviation was "the "fastest growing source" of carbon dioxide emissions in Britain.

"But rather than taking steps to curb the rise in air travel, the government is encouraging it by giving the aviation industry multi-billion pound tax breaks and allowing UK airports to expand."

Blair sought to put the issue in perspective, pointing out that, even if Britain reduced its carbon emissions to zero tomorrow, emerging economy China would make up the difference within two years.

"So we've got to be realistic about how much obligation we've got to put on ourselves," he added.

"The truth is all the evidence is that if you use the science and technology constructively, your economy can grow, people can have a good time but, do so more responsibly."

Politicians had to be realistic about how many sacrifices the public is willing to make, he said. Asking people to cancel their holidays to save the environment was going too far, he suggested.

"I'm still waiting for the first politician who's actually running for office who's going to come out and say it -- and they're not."

Blair's comments come after a furious public row last week between climate change minister Ian Pearson and the outspoken boss of no-frills airline Ryanair Michael O'Leary.

Pearson described Ryanair as "the irresponsible face of capitalism", accusing them of failing to recognise the problem. O'Leary retorted, saying Pearson was "foolish and ill-informed".

Transport Minister Douglas Alexander denied Tuesday that there was any difference between Blair and Pearson over the issue.

"What we're saying is that the rightway forward for airlines, including Ryanair (is to) recognise that they do have a responsibility," he told BBC Radio Four's Today programme.

At the same time airlines and authorities need to "have an intelligent debate to see what is the most appropriate way for aviation to meet its environmental externalities," he added.

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