People living near Stansted Airport have mounted protests

Transport Secretary Alistair Darling is due to publish the government's Aviation White Paper, setting out a 30-year plan, on Tuesday.

It must address how the country is going to cope with a massive predicted increase in demand for air travel.

The construction of an extra runway at Stansted and Birmingham airports is expected to be the government's preferred option.

Expansion of existing capacity at Edinburgh, Glasgow, Bristol, Cardiff, Manchester and Belfast International is also likely.

We absolutely need another runway at Heathrow in order for our business to grow BA government and industry director Andrew Cahn

New airports - under consideration on the Thames Estuary at Cliffe in north Kent and the Severn Estuary, near Newport in South Wales - are thought to have been shelved.

But whatever Mr Darling announces is bound to provoke opposition from some.

Environmentalists are opposed to any new runways at all, let alone new airports, saying the government should manage the increased demand by scrapping subsidies and raising tax, which would increase the cost to passengers of air travel.

Friends of the Earth claims that while aviation accounted for 5% of UK CO2 emissions in 2002, this could rise to 10-12% by 2020.

'Enormous damage'

Its director Tony Juniper said if the government allows more runways to be built "it will show that protecting the planet is a low priority, regardless of the PR spin".

"Air travel causes enormous damage including air and noise pollution, and is the fastest growing source of climate changing gases - a truly sustainable White Paper would get rid of the tax breaks that prop up the industry rather than caving in to its demands," he said.

The Woodland Trust has warned that if Stansted gets another runway, the development could destroy or damage 86 hectares of ancient woodland.

But the airline industry has been taking a very different view.

If there is no development at Heathrow we will lose what we have now - Europe's number one hub which earns Britain billions of pounds a year Jim McAuslan Airline pilots' union Balpa

British Airways says two extra runways for the South East could generate �65bn of economic benefits

Government and industry director Andrew Cahn told BBC News: "We absolutely need another runway at Heathrow in order for our business to grow."

The country's biggest airport operator, BAA, is calling for up to three new runways to be built.

It believes not building runways would cause significant damage to Britain's economic position in the world.

Jim McAuslan, general secretary of airline pilots' union Balpa, said he hoped to hear plans for a third runway at Heathrow, and further runways at Gatwick and Stansted.

"One new runway will never cope with the rising demand," he said.

"If there is no development at Heathrow we will lose what we have now - Europe's number one hub which earns Britain billions of pounds a year."

He also hoped the government would not impose a higher Airline Passenger Duty, which was another option for coping with the increased air traffic.

'No more tax' plea

But Tony Grayling, associate director of the Institute for Public Policy Research (IPPR), warned that simply building to meet demand would repeat the mistake made in road policy during the 1980s.

"The government must reject the siren calls of the aviation industry to build as many runways as it takes to accommodate growth at all costs," he said

"Instead, the growth in air transport should be managed, respecting global and local environmental limits, ensuring that aviation pays its environmental costs and promoting balanced regional economic development."

Environmental campaigners say the runway-building would be unnecessary if the government scrapped the industry's tax breaks.

Sustainable transport pressure group Transport 2000 has called for a package of measures, including a significant rise in Air Passenger Duty, VAT on all aviation transactions, a firm commitment to an EU emissions charge and take-off and landing slot auctioning at the main airports.

Whatever he announces, Mr Darling has been urged to produce a clear vision.

Local government aviation group SASIG warned that if he "dithered" over the White Paper it would lead to uncertainty for thousands of residents living near airports.