Proposals to build new airport runways in an attempt to cope with rising UK demand for air travel have been unveiled by the government.

They include the possibility of three extra runways at Stansted, one more at Heathrow airport near London - moves strongly opposed by local residents and environmental groups.

	:	UK airport expansion
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Glasgow or Edinburgh could also get another runway if the proposals are adopted, with expansions at airports like Bristol and Birmingham also on the cards.

UK air passenger numbers are expected to more than double from 180m a year to 400m by 2020, according to Mr Darling.

Transport Secretary Alistair Darling told MPs that one option in the south east was expansion at Heathrow - possibly an additional shorter runway.

Airport expansion proposals

Three new runways at Stansted Short runway at Heathrow New runway at Birmingham or East Midlands Two runway airport between Coventry and Rugby Major new terminal at Manchester Possible expansion of Bristol airport Expansion of Cardiff airport New runway in Scotland by 2030 No expansion at Gatwick before 2019 Option of new airport at Cliffe, in north Kent Possible expansion of Luton Freight airport at Alconbury

Another option would be to expand Stansted either into a new hub airport or to complement services at Heathrow.

Expansion at Luton would be looked into and a possible freight airport at Alconbury, near Huntingdon in Cambridgeshire, was on the cards.

A new airport could also be built near the River Thames at Cliffe in north Kent.

A new runway at Gatwick is another idea that is on the table but any changes there are likely to be delayed until 2019 when a non-expansion agreement runs out.

Mr Darling said that the government would not challenge that agreement.

The government's consultation document also proposes converting defunct RAF bases into civilian airports.

RAF Finningley in Yorkshire is one of the bases that has been touted.

If converted it could provide an international airport for Doncaster.

For the Conservatives, new shadow transport secretary Tim Collins said he recognised the need to expand capacity but questioned whether the government had over-estimated future growth.

While the Liberal Democrat's Don Foster expressed concern over the potential for increased nightflights.

White Paper

The proposals will go out to consultation ahead of the publication of the government's White Paper on aviation due next year.

Mr Darling insisted: "Doing nothing is not an option."

Darling: Launching consultation

The government would ensure the UK could meet increased demand, using existing capacity where possible while making sure the environmental effects are dealt with, he said.

"We have the fourth largest economy in the world based largely on our ability to trade. Something like a third of exports go by air ...

"Frankly, doing nothing is not an option. If we went down that route, we would undoubtedly put the country's increasing prosperity at risk, we would cause air fares to go up and we would not actually be dealing with what is a very real problem."

Employs 100,000

Mr Darling said half the UK population fly at least once a year and a quarter of the population fly twice or more a year.

Heathrow is an international hub airport that employs 100,000 people.

"The question is do you build on Heathrow, an existing airport, or do you go to another one of London airports and expand there, either to take the place of Heathrow or to complement it or do you go for a new build airport at another site?" said Mr Darling.

Cliffe 'a non-starter'

Speaking on the BBC's Ten O'Clock News, the BBC's transport correspondent Simon Montague said: "I think Cliffe is a complete non-starter, not a cat-in-hell's chance.

"It's far too expensive and the economic benefits are pretty low.

"In south-east England that means only one thing, you're left with a racing certainty of another runway at Stansted and the aviation industry will push extremely hard to try to get a new short runway at Heathrow."

Friends of the Earth attacked the proposals even before they had been made public, saying the government's regional studies were "flawed and rigged".

New campaign group AirportWatch, which launched last week, said the government should be looking at reducing the amount of air travel as the increased demand simply could not be met.