A 50-year-old international agreement means airlines pay no duty on the fuel they use, whereas motorists and coach operators have to pay more than 40p a litre.

Protests at airport expansion plans

The group claims air travel is the fastest growing source of greenhouse gases, which are overheating the atmosphere.

It also says air travel is responsible for about 7% of global warming, including 3% of carbon dioxide emissions.

FoE has written to the Chancellor Gordon Brown asking him to back calls for a Europe wide tax on aviation kerosene.

Roger Higman: "We want the aviation sector to pay"

Roger Higman, FoE senior transport campaigner, said: "Flying is the most polluting form of transport there is. Yet airlines pay no duty on the fuel they use and therefore have little incentive to conserve fuel or control their emissions.

"The tax exemption gives airlines an unfair advantage over other forms of transport, encouraging people to travel in the least environmentally friendly way.

"The chancellor must back European moves to end this loophole by taxing airlines for the fuel they use."

'Anomaly'

In a statement, the Treasury agreed the tax exemption on aviation fuels was "an anomaly".

But it said "taxing an international industry in one region or country could lead to competitive distortions; aircraft could avoid paying such a tax by carrying extra untaxed fuel and the increased weight would cause even more harmful emissions".

Le Thi Mai from the Association of European Airlines: "If we are polluting we should pay"

Airlines argue that heavy taxes would only reduce the amount of money for environmental improvements, forcing ticket prices up.

The call by FoE comes as Deputy Prime Minister John Prescott and Environment Minister Michael Meacher go to Argentina next week to take part in the climate change summit.

The UK is pledged to a 12.5% reduction in its greenhouse gas emissions. The government hopes to meet an ambitious manifesto pledge of a 20% cut by 2012.