Fifteen environmental protesters were arrested on Wednesday after they blocked the roads outside the Houses of Parliament in London.

More than 1,000 members of the Extinction Rebellion group issued a declaration of rebellion in Parliament Square to try to draw attention to the unfolding climate crisis.

They then sat down in the road, blocking one of London's busiest intersections for two hours.

Speakers included Guardian columnist George Monbiot.

The protest came a day after scientists warned that humanity has wiped out 60 percent of mammals, birds, fish and reptiles since 1970.

The UN warned recently that there are only 12 years left to prevent climate catastrophe.