His serious aviation habit means he is hardly the best person to lecture others on the environment. But John Travolta went ahead and did it anyway.

The 53-year-old actor, a passionate pilot, encouraged his fans to "do their bit" to tackle global warming.

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Happy landings: John Travolta's plane collection parked at his home in Florida

But although he readily admitted: "I fly jets", he failed to mention he actually owns five, along with his own private runway.

Clocking up at least 30,000 flying miles in the past 12 months means he has produced an estimated 800 tons of carbon emissions – nearly 100 times the average Briton's tally.

Travolta made his comments this week at the British premiere of his movie, Wild Hogs.

He spoke of the importance of helping the environment by using "alternative methods of fuel" – after driving down the red carpet on a Harley Davidson.

Travolta, a Scientologist, claimed the solution to global warming could be found in outer space and blamed his hefty flying mileage on the nature of the movie business.

But his appointment as a "serving ambassador" for the Australian airline Qantas doesn't seem to have much to do with the movies. Nor does a recent, two-month round-the-world flying trip.

"It [global warming] is a very valid issue," Travolta declared. "I'm wondering if we need to think about other planets and dome cities.

"Everyone can do their bit. But I don't know if it's not too late already. We have to think about alternative methods of fuel.

"I'm probably not the best candidate to ask about global warming because I fly jets.

"I use them as a business tool though, as others do. I think it's part of this industry – otherwise I couldn't be here doing this and I wouldn't be here now."

Travolta's five private planes – a customised £2million Boeing 707, three Gulfstream jets and a Lear jet – are kept at the bottom of his garden in the US next to a private runway.

Indeed, such is his enthusiasm for flying, he persuaded his wife, actress Kelly Preston, to name their son Jett when he was born 14 years ago.

Five years ago he piloted his own Boeing 707 on a 13- city "Spirit of Friendship Tour" for Qantas, taking in Los Angeles, Auckland, Sydney, Singapore, Tokyo, London, Paris and New York and amassing over 35,000 flying miles.

More recently, a gruelling promotional schedule for his two latest projects, Hairspray and Wild Hogs, has seen him fly extensively over the past year.

This includes a country-wide tour of the US and a visit to Canada as well as this week's appearance in Leicester Square.

Such prolific mileage means that, over the past 12 months, he has accumulated around 800 tonnes of carbon emissions.

According to a recent study by the government-funded Carbon Trust, this means he boasts a carbon "footprint" nearly 100 times that of the average Briton, who is responsible for 10.92 tons of Co2, from his flights alone.

One of the world's leading climate change businesses, the Carbon Neutral Company, has written to Travolta, suggesting ways he could reduce these alarming levels.

He has yet to respond to their advice. Environmental groups were quick to criticise Travolta for "discrediting the cause".

John Buckley, managing director-of CarbonFootprint.com, said: "John Travolta has such a high-profile celebrity status, so what he says carries an extraordinary amount of weight.

"So it is such a shame when someone of his standing is so outspoken about green issues, yet fails to practise what he preaches.

"Unfortunately someone of his standing ends up discrediting the cause itself, because he is saying people should protect the environment on one hand, yet traveling on a private plane on the other.

"Green issues are serious and should be treated as such.

"It is vital for celebrities to toe the line when they speak out in support of it."

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