Activists behind an annual climate change camp today threatened to close down Heathrow in an early sign of direct action aimed at stopping a controversial third runway being built.
Leaders of the annual event will meet later this month to discuss future demonstration, including some which they warned would be aimed at shutting the airport down completely.
The development came as a group calling itself the Climate Suffragettes smashed glass doors at the London offices of the Department for Transport (DfT)in protest at the Government's go-ahead for Heathrow's expansion.
One of the activists behind the annual climate camp pledged: "We will be the spanner in the works of third runway construction."
The group pointed out that at the 2007 camp, which was held near Heathrow, about 2,000 people decided not to shut the airport itself, but target BAA's offices.
"The Heathrow decision makes the option of shutting down the world's busiest airport a potential next step in the escalating campaign to stop the runway being built," said one of the activists.
Sally Wintour, who took part in the 2007 camp, said: "Gordon Brown is prioritising the profit margins of BAA and the aviation industry over the climate and the local community of Sipson.
"We invite anyone in the UK who has lain awake and worried about climate change and their children's future to come down and join us in using direct action to prevent this ecological and social catastrophe from unfolding."
Harry Whittaker, an anti-aviation campaigner, said: "Gordon, BAA and the construction companies had better start factoring in how many more millions it is going to cost to build this runway once they have to deal with the daily consequences of direct action.
"This decision flies in the face of popular opinion, and if the political channels to stop it have been unsuccessful, it's important that people use direct action to prevent this climate disaster."
A so-called "flashmob" will be held at Heathrow at midday tomorrow by a range of anti-aviation expansion groups and more action is being planned.
The Climate Suffragettes said three women wearing red sashes hurled bricks at the doors of DfT's Westminster building at 4am.
The bricks were wrapped in notes that read: "No third runway, the Suffra-jets are back," they said.
They also said they had hurled green paint "to symbolise the greenwash they heard from the Government".
A spokeswoman for the group, which compares itself with the 20th century campaigners for votes for women, said: "The Government has opened the floodgates for radical action."
Conservative leader David Cameron today issued a clear warning to industry not to invest money and energy in the proposed third runway at Heathrow, as he reaffirmed his party's commitment to scrap the project if it won power.
Some observers have suggested that the green light given by Transport Secretary Geoff Hoon yesterday represented a guarantee that it would go ahead, as the scheme would be too far advanced by the time of the next election for an incoming Tory administration to halt it.
But Mr Cameron today flatly rejected this assumption, stating: "The third runway is just not going to happen."
In an interview with The Guardian, he insisted that he did not believe that a Tory Government would be required to pay compensation if it scrapped the scheme.