Charles puts his (carbon) foot in it

During the trip he plans to emphasise the importance which the British Government places on climate change as a key international priority.

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To underline his commitment to reducing his 'carbon footprint' - the amount of carbon dioxide pumped into the atmosphere during the flight - he is to travel by scheduled flight instead of a chartered or private jet.

But he and his 20-strong party will travel exclusively in the first and club class sections where there are a total of 62 seats.

This means their effective 'carbon footprint' is three times what it would be if every seat was used and the short return trip to New York will result in the emission of 24 tonnes of carbon dioxide.

To 'offset' this, the prince would need to pay £177.60 to plant trees.

Charles and Camilla will visit Philadelphia and New York on a two-day visit to America on 27 and 28 January.

The Prince is to receive the Global Environmental Citizen Award from Harvard Medical School's Centre for Health and the Global Environment, from last year's recipient, former Vice President and Presidential candidate Al Gore and actress Meryl Streep.

He is to be praised for highlighting the importance of the environment.

The Prince, who has described climate change as the 'biggest threat to mankind', is also planning to publish details of his own carbon footprint - a measure of how his activities have had an impact on the environment in terms of the amount of green house gases produced - as part of his 2007 accounts.

In November it was revealed that he planned a green revolution at his office.

The radical shake-up included getting staff to use bicycles to help the fight against global warming. He said he was even prepared to travel to London by commuter train from a station near Highgrove.

Charles told aides he also wanted to stop using gas-guzzling royal helicopters and private jets on official engagements whenever possible and intended to make more use of the royal train and to find a more environmentally-friendly fuel for his fleet of cars.

In December Charles officially announced his plans saying he may cut down on official engagements to live a greener lifestyle.

Senior courtiers said changing his travel programme may result in the prince carrying out fewer official duties each year.

His spokesman Paddy Harverson said at the time: "One of our main targets will be to reduce the number of flights the prince uses in the UK each year."

The cost of Charles and Camilla's weekend visit to New York will be significantly less than the £280,186 to taxpayers for his last official trip to America in November 2005.

With a hefty discount negotiated with British Airways the cost is still expected to be around £100,000. If he had paid full fare for the 14 first class seats and 48 business class seats the return flight would have cost £281,530.

Last year Charles spent £1.1 million on private planes and helicopters, including £304,000 on a private jet for his official tour of Egypt, India and Saudi Arabia.