Warren Buffett's Berkshire Hathaway conglomerate who owns Net Jets, the private jet company, is making carbon offsetting obligatory for its customers.

The bill of all new customers at its European operations will bear the cost of offsetting their flights, the company will be declaring today. The cost of a Net Jets customer will increase about €4,000 (£2,720), said NetJets.

"I am sure there will be a few but I think this will add a lot of lustre to our brand. Our client base tends to be well-educated and sophisticated people. They have driven this initiative and should share a lot of the credit", said Mark Booth, chairman of NetJets Europe, refuting the damage sales charge.

Mr Booth affirmed that three of NetJets' top five customers have signed up for the carbon offsetting scheme voluntarily. Others will sign up it when they will renew their contracts.

Professor Dan Esty, an environmental academic, at the Davos forum said, "This is a unique programme that will set the bar for everyone else". EcoSecurities, an Oxford-based company will receive investments from Net Jets for carbon offsetting projects encouraging tree planting that atone for the negative effects of the carbon dioxide they generate.

A part-share in aircraft of 50 hours of flights per year, or a Net Jets card offering 25 hours of flights over two years is offered to 1,500 European customers by Net Jets.

The €4,000 price increase would affect to its average aircraft part-owner customers, said the company.