Four members of Greenpeace have been arrested after climbing atop a plane at London's Heathrow Airport and unfurling a banner protesting climate change.

The environmentalists walked across the airport tarmac and climbed onto the British Airways Airbus A320 after it landed on a domestic flight from Manchester.

The two men and two women wrapped a banner around the tail fin reading: Climate Emergency — No Third Runway.

Greenpeace opposes plans for a third runway at Heathrow, Europe's busiest airport.

Heathrow operator BAA PLC says the four protesters were arrested after about 90 minutes and taken to the airport's police station.

It called the protest "unlawful and irresponsible" and said it's investigating the security breach.