Veterans of last year's Heathrow climate camp are holding a mass meeting to protest against airport expansion plans today before joining a three-day "climate caravan" across southwest London.

The Heathrow conference kicks off in Harlington at noon with delegates from last year's Camp for Climate Action, campaign groups HACAN and NoTRAG (No Third Runway Action Group), and Greenpeace.

Following the conference, the difference groups are expected to join a "climate caravan" on their journey to Kingsnorth in Kent where this year's camp will be held in protest against energy company Eon's plans to build a coal-fire power station.

The caravan is expected to take three days to travel from Heathrow south to Richmond then snake its way along the river through Putney, Wandsworth and Battersea before continuing on to Kent mass protest.

Last August thousands of people spent a week camping in a field in the village of Sipson, which will be destroyed if Heathrow expansion goes ahead, to draw attention to the threat of climate change.

The Heathrow conference will run from noon to 5pm today at the Harlington Baptist Church, High Street, Harlington.

A spokesperson for the Camp for Climate Action said: "The threat of climate change becomes ever more real.

"Although we are concentrating our efforts this year at Kingsnorth where the Government is proposing to build a new coal-fired power station, we have not forgotten Heathrow.

"We are determined to stop any expansion of the airport. At the conference we will be discussing with local residents and fellow environmental organisations the most effective ways of doing just that."

John Stewart, the Chair of HACAN, said: "This conference will be a visible sign to the Government that its many opponents are working closely together.

"People coming from different backgrounds will be sitting down together to discuss a wide range of ways of continuing to oppose expansion, from mass letterwriting to mass direct action.

"What unites us is an utter determination to win this battle."