Transport Secretary Alistair Darling unveiled a massive expansion programme for Britain's airports in a statement to the Commons.

The proposals which have gone out for consultation are aimed at meeting a rising demand for air travel in the UK.

Mr Darling is seeking views on whether either Glasgow or Edinburgh should become a "hub" for air travel north of the border.

Alistair Darling: Consultation exercise

He is also consulting on whether extra capacity should be concentrated at one or two Scottish airports or spread across the country.

The UK Government predicted that Scotland would need one new runway by 2030.

Options outlined on Tuesday included extending the runways at Edinburgh and Glasgow airports, or creating an extra runway at either of the two airports.

The government is also suggesting that Aberdeen, Inverness and Prestwick airports will need to be upgraded.

Mr Darling told MPs that the government wanted to encourage the development of regional airports in the UK.

"Over the last 10 years the number of people using the main Scottish airports has doubled to 16 million a year, and we expect continued growth as the Scottish economy expands," he said.

Key airports

"The consultation paper looks at making the most out of existing capacity.

"It asks where new capacity should be situated - should it be concentrated on one or two key airports or should it be spread across all Scottish airports.

"And it asks what scope there is to develop Edinburgh or Glasgow as a hub airport for Scotland, attracting new services to a wide range of destinations."

The government is simply following a misguided predict and provide policy that will encourage a highly polluting method of transport

Robin Harper Green MSP

Mr Darling said the consultation would also consider other issues of concern to Scotland, such as maintaining access to London and the lifeline air links to the Highlands and Islands.

He added that the Scottish Executive was also publishing a report on how to improve rail links to both Edinburgh and Glasgow airports.

Scotish Transport Minister Iain Gray stressed that no decision has been taken on which airport would get a new runway but said that "Edinburgh and Glasgow are our key airports".

He said: "It's clear that passenger numbers and traffic is increasing both at Glasgow and Edinburgh and it's also clear that both airports have particular strengths.

"What we will do is ensure that we safeguard those expansion options so there will be some decisions that have to be taken in order to keep that option open 10 years in the future."

Iain Gray: No decisions taken

Tom Wilson, managing director of Prestwick Airport, said it would be "erroneous" to consider expansion only at Glasgow or Edinburgh.

Mr Wilson said Mr Darling had mentioned that one of the options was to make the most of existing capacity.

He said: "Beyond doubt, the most existing capacity that is unused is at Prestwick.

"We have the longest runway in Scotland, we have parallel taxi-ways the whole length and we have our own rail link already in place."

Duncan Tannahill of Glasgow Chamber of Commerce pointed out that the city's airport handled more passengers than Edinburgh.

Travel options

But he said: "I have a real concern that Glasgow could lose out in this debate in the long-run and that is a very unpalatable option for the west coast of Scotland.

"I think it is key that the infrastructure has to be right in Glasgow for the sake of the economy now and in the future."

However, Green MSP Robin Harper voiced his party's opposition to any expansion in airport facilities.

He said the government should support "more environmentally friendly" travel options.

"By building yet more airports and runways the government is simply following a misguided predict and provide policy that will encourage a highly polluting method of transport," he said.