HUNDREDS of demonstrators will stage a "flash mob" protest against airport expansion when Heathrow's £4.3bn Terminal 5 (T5) opens for business today.

Formed by local residents and what are described as "environmental activists", the protest at T5 will, according to organisers, be a "peaceful and legal event".

Flash mobs involve a large number of people who assemble in a public place and perform an unusual act for a brief time before quickly dispersing. The protest is against plans to build a third runway at Heathrow and a sixth terminal.

Environmental campaigner Andrea Needham, said: "The flash mob is a fun event but with a serious purpose. Airport expansion is totally irresponsible in the face of the devastating effects of climate change."