Climate protesters expanded their Heathrow airport action on Monday, with small groups demonstrating outside Sizewell nuclear power plant and BP's London headquarters.

The Camp for Climate Action spread their protest to Sizewell "A" and "B" on the last day of the week-long Heathrow environmental demonstration held against plans to build a third runway.

About six members chained themselves together across the road to the Suffolk plant in an attempt to prevent traffic going into the main entrances.

"We oppose the myth that nuclear power is carbon-neutral and a solution to climate change," said Paul Bruce, a spokesman for the camp.

The action was organised in protest at government proposals to build new nuclear power stations and to draw attention to the problem of dealing with nuclear waste, the group added.

In another protest, about a dozen activists glued their hands to entrance doors at oil firm BP's headquarters in central London.

The camp was considering extending its Heathrow protest for three hours until 3 p.m., organisers said.

Scuffles broke out at the entrance to the headquarters of the operator of Heathrow airport, BAA, when activists tried to prevent members of staff getting to work.

About half BAA's normal numbers turned up, with the rest working at other buildings or from home, a BAA spokesman said.

He said protesters had failed to disrupt operations.

Bruce however said the demonstrations had been successful.

"We never intended to disrupt planes," he said. "Our intention was to blockade BAA's headquarters, which has been successful.

"We wanted to highlight the selfishness of business in wanting a third runway, and that has been successful. We have also built a social movement."

Between 100 and 150 camp members remain at the site, the BAA spokesman said.

About 20 activists have been arrested at the camp, with a further 40 detained at different sites including the Department of Transport and Biggin Hill airport.

Eight were arrested on Sunday on suspicion of aggravated trespass after an incident outside a BA world cargo site near Heathrow.