"Today marks a vital breakthrough for the whole airline industry," Virgin founder Richard Branson told reporters in a hangar at Heathrow airport prior to the flight's departure.

British billionaire Branson said, however, it was unlikely the nut of the wild growing babassu palm would play a key role as airlines turn to renewable fuel sources to cut the industry's greenhouse gas emissions.

"We did not want to use biofuels such as corn oil which were competing with staple food sources," he said, adding he believed algae produced in places like sewage treatment farms were the most likely future source of renewable fuel for the airline industry.

Biofuels, which are currently mainly produced from crops such as grain, vegetable oils and sugar, are seen by advocates as a way to cut emissions of greenhouse gases and reduce dependence on fossil fuels.

There has been concern, however, that an expansion in the area of crops grown for energy has helped drive up food prices, and some scientists have questioned the environmental benefits of so-called first generation biofuels.

Many scientists believe so-called second generation biofuels, which could be made from products such as municipal waste, will provide more substantial environmental benefits without competing with food crops for land.

The biofuels blend on the Virgin flight contained 20 percent neat biofuel and 80 percent conventional jet fuel. Branson said tests had shown it was possible to fly with a 40 percent blend.

Branson, whose Virgin Group business spans an airline, a rail service, drinks, hotels and leisure, has committed to spending all the profits from his airline and rail business to combat global warming by cutting carbon emissions.

Last year, Virgin started to power some of its trains using a fuel containing 20 percent biodiesel produced mainly using British rapeseed oil blended with US soybean oil and palm oil from the Far East.