London (CNN) At least 276 Extinction Rebellion protesters have been arrested in London as campaigners begin two weeks of demonstrations demanding that governments take action on the climate and ecological emergency.

The Metropolitan Police said 276 people had been detained by 6:15 p.m. (1:15 p.m. ET) as activists shut down roads around Parliament and across large parts of Westminster in the UK capital.

The action is part of a larger coordinated movement called International Rebellion; protests are expected to take place in 60 cities worldwide.

Activists gather on Westminster Bridge during the protests.

"Despite a culture of fear being spread by (the) government in the run up to the Rebellion -- several thousand people ... blocked sites, roads and locations across Westminster," Extinction Rebellion wrote online

"There is no Plan(et) B. The government doesn't have one. The things we trust in life that we don't even know we trust, they're all incredibly fragile. Extreme weather will tell this truth for us unless the government does it for us first."

Climate change activists block The Mall as they demonstrate near Buckingham Palace.

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