Budget airline Ryanair (LON:RYA) has called for three runways at London's trio of major airports after a UK government-sponsored commission recommended expanding Heathrow.
Ryanair said the commission's proposal to add a third runway at Heathrow would not solve the shortage of airport space in south-east England.
The Irish carrier said the British government should allow each of the three London airports, Heathrow, Gatwick and Stansted, to build three competing runways.
It claimed such a move would solve the capacity crisis in the south-east for the next 100 years.
A Ryanair spokesman added: "It remains a fact that additional runways in Stansted and Gatwick can and will be delivered much earlier than any Heathrow third runway.”
The commission, led by former Confederation of British Industry chief Howard Davies, backed a third runway at Heathrow after a three-year study of ways to expand south-east airport capacity.
As well as a third Heathrow runway, it short-listed two other options including a second runway at Gatwick and extending one of Heathrow's two existing runways.
Davies said: "Heathrow ... provides the greatest benefits for business passengers, freight operators and the broader economy."
But the proposal is likely to be regarded with some trepidation by Britain's Conservative government, many of whose MPs have constituencies around Heathrow or under the flight path.
The Tories are unlikely to want to risk undermining their core voter support and causing a parliamentary rebellion at a time when they have a wafer-thin majority at Westminster.
A previous plan to expand Heathrow was ditched in 2010 amid political opposition and there are doubts as to whether the latest proposal will be accepted.
Heathrow and many business leaders have claimed expanding the London hub is the best way to boost the UK economy and compete with airport rivals such as Paris, Amsterdam and Frankfurt.
BA and Iberia owner IAG (LON:IAG) urged the government to act quickly on the plan to expand Heathrow, but warned that airlines would not pay for it.
Chief executive Willie Walsh said: “The real test is whether any political will exists to turn (Davies') recommendation into reality.
“Without political vision and leadership, it will end up on the shelf gathering dust like its predecessors.
“Even with political consensus, Sir Howard believes naively the costs associated with the scheme would be borne by airlines. While we believe it would be outrageous to burden passengers with the cost of such expensive infrastructure, we will not pay for it.”
Heathrow's chief executive John Holland-Kaye said its expansion plan would take the concerns of local communities into account and would meet carbon, air quality and noise targets.
"Expanding Heathrow will keep Britain as one of the world's great trading nations, right at the heart of the global economy," he said.
Gatwick airport said it remained confident that it will still be chosen for expansion as it was the only achievable option.