Environmental activist group Extinction Rebellion shut down four key London thoroughfares on Monday, including Waterloo Bridge and Oxford Circus, at the start of a multi-day protest designed to bring the city to a standstill.  The group, which is calling for urgent action to prevent climate change, said its protesters were preparing to camp overnight and maintain the London blockades for “as long as possible”, potentially up to two weeks, or until the government agrees to talks. It has attracted high-profile supporters including Rowan Williams, the former Archbishop of Canterbury, but also been criticized for its disruptive and often illegal tactics.

On Monday similar protests by Extinction Rebellion’s international groups were planned in more than 80 cities in 33 countries, from Melbourne in Australia to Accra in Ghana and Berlin, the German capital. The group is calling on the UK government to declare a climate emergency, slash greenhouse gas emissions to net zero by 2025, and create a “citizens’ assembly” that will debate climate issues.

The several thousand protesters set up a temporary garden of trees and plants across the center of Waterloo Bridge, parked a pink boat in the middle of Oxford Circus, blocked roads around Marble Arch and gave speeches in Parliament Square. They also temporarily blocked Piccadilly Circus.