Activists held after rooftop stunt

The five activists from campaign group Plane Stupid unfurled two huge banners over the historic building and remained on the roof for three hours, gaining huge publicity and landing the Government with embarrassing questions about security levels.

The three men and two women said they gained access to Parliament as visitors, walked through the building, got into a lift and then climbed on to the roof.

It was the second security breach this week, following an incident at Heathrow on Monday when five Greenpeace activists managed to climb on top of a British Airways plane in protest against expanding the airport.

The latest protest ended shortly after Gordon Brown stood up in the Commons for Prime Minister's Questions. Pointing to the roof, he told MPs: "The message should go out today very clearly that decisions in this country should be made in the chamber of this House and not on the roof of this House.

"It is a very important message that should be sent out to those people who are protesting."

Police arrested the five under the Serious and Organised Crime and Police Act.

Westminster sources said they believed the two banners, which read No Third Runway and BAA Headquarters, were stored inside the Commons for the protesters to collect on Wednesday morning.

The demonstration came on the final day of the Government's consultation on expanding Heathrow airport, including a third runway.

John McDonnell, Labour MP for Hayes & Harlington, which covers Heathrow airport said: "Direct action is an inevitable consequence of Government refusing to listen to communities under threat and to the threat to our planet from climate change."