'We're living on borrowed time', claims Charles

In a forthright speech in front of leading figures, including Prime Minister Tony Blair, the Prince said: 'We are consuming the resources of our planet at such a rate that we are, in effect, living off credit and living on borrowed time.

'It is our children and grandchildren who will have to pay off this debt and we owe it to them and ourselves to do something about it before it is too late.'

The Prince launched his Costing The Earth — The Accounting For Sustainability project at a forum at St James s Palace attended by politicians and business and faith leaders.

They included the Archbishop of Canterbury Dr Rowan Williams, Lord Browne, chief executive of BP, and former US vice president Al Gore, a leading environmentalist whose film An Inconvenient Truth warns the world must act now to save itself.

The former Democratic US presidential candidate praised Charles's green initiative in a video message to the forum. He said it may be 'one of the most important initiatives' and stressed: 'We need to continue the effort to solve the climate crisis.'

The heir to the throne is determined to reduce his carbon footprint on the world. He encourages his staff to make trips around the capital on bicycle instead of taking cars or cabs.

Actor Stephen Fry and comedian Al Murray have teamed up to make a film in support of the Prince. Fry, a close friend of Charles, plays Planet Earth while Murray, otherwise known as the Pub Landlord, stars as the Moon in the appeal.

The Prince is set to label all his Duchy Originals range with details of greenhouse gases made during their production. The Queen has already gone green at Windsor Castle with a plan to use hydroelectric power.

The Duke of Edinburgh uses a taxi cab fuelled by liquid petroleum gas to travel around London, while water in a bore hole at Buckingham Palace is used to supply air conditioning to the Queen's gallery before topping up the water levels in the Palace lake.

Mr Gore visited Britain in September to promote his film. Charles is said to have met him privately at Highgrove to discuss their mutual passion for the environment.