Thirteen people were charged Tuesday after climate change protesters accessed a runway at Heathrow Airport and staged a demonstration against a proposed airport expansion that caused flight cancellations and delays.

Campaigners from direct action group Plane Stupid got onto the northern runway at 3:30 am (0230 GMT) on Monday and tied themselves together with bicycle locks, causing 22 flights to be cancelled.

A video uploaded onto the Internet showed several activists attached to a police officer who was telling them: "You are causing severe disruption and it will be in the millions of pounds because it will take us a while to remove you."

A group of men and women have been charged with aggravated trespass and entering a security-restricted area of an aerodrome, Metropolitan Police said.

The 13 will appear at Uxbridge Magistrates' Court in west London on August 19.

The police earlier confirmed security at the airport would be reviewed following the protest.

"The Metropolitan Police Service works closely with Heathrow Airport Limited to keep those who use or work at Heathrow safe and secure," a spokesman said.

"The Metropolitan Police and Heathrow will jointly review today's protest incident at the airport and make necessary changes to the security plan."

Earlier this month a British government-appointed commission recommended building a third runway at Heathrow rather than at rival airport London Gatwick, south of the capital, in order to increase capacity.

After three years of investigation, the Airports Commission said Heathrow was best placed to provide "urgently required" capacity, but environmentalists warned that building a new runway there would make it harder to reduce air pollution and climate change emissions.