Environmental campaigners have accused the aviation industry of going back on a promise not to lobby for a third runway at Heathrow airport.

Friends of the Earth compiled a "chronology of promises" dating back to 1993, in which the British Airport Authority (BAA) said it they would not back such a project.

The organisation also points to the Terminal Five planning inspector's report, backed by the company, which ruled out a third runway - claiming it would have "unacceptable environmental consequences".

However, in a statement to the Commons in late July, transport secretary Alistair Darling included the option in the government's consultation paper on airport expansion.

"With Heathrow, we have a world-class hub airport. Some 15 million international passengers transfer through the airport - the biggest number at any airport in the world - and it employs 68,000 people directly, but Heathrow is already under pressure. Airlines cannot get the runway slots to operate new services. It is already at its limit," he said.

However, Friends of the Earth condemned any expansion of the West London airport.

"The aviation industry is trying to weasel out of repeated promises to the public, media and the government that a third runway at Heathrow would never be needed," said aviation campaigner Roger Higman.

"The industry's well-paid and unscrupulous lobbyists shower these promises around like confetti - presumably hoping that the public will forget what was said when the next development comes along. Terminal Five came with the usual pledges that this would be the industry's last 'territorial claim' in West London. Well, it wasn't.

"There will be no end to expansion - until the government takes steps to bring the lumbering monster of civil aviation back under control."

BAA described the issue as "a complicated debate".

"BAA believes there is a very strong case for providing more runway capacity (and the supporting terminal and other infrastructure) in the South East of England," a spokeswoman said.

"We will review all the options presented by the government and comment on them in due course."