Railways throughout Europe could be boosted as part of an EU energy policy.

"We must revitalise the railways, reorganise the road transport sector, rationalise the use of conventional private cars, and promote more environmentally friendly and efficient modes of transport," says a green paper issued by the Commission.

The paper also calls for "redressing the growing imbalance between road haulage and rail" and for a "truly alternative transport policy".

It adds: "Could corrective action be taken, however unpopular, notably to encourage lower use of cars in urban areas?"

The green paper was launched by transport and energy commissioner Loyola de Palacio.

Transport campaigners are also calling on the European Union to develop green tourism as part of an EU sustainability strategy, expected to be published later this year.

Tourism and leisure traffic accounts for half of all European transport, but the share of leisure rail travel is down to 15% and falling while air travel is growing rapidly.

In an attempt to shift more holiday journeys on to public transport, it is suggsted that there should be road charging per kilometre, increased take-off and landing charges for flights shorter than 500 miles, a tax on aviation fuel, higher parking fees at tourist venues and promotion of door-to-door luggage transport by rail.