Extinction Rebellion climate change activists blocked London's Vauxhall and Lambeth bridges on Sunday.

Hundreds of protesters prevented cars and buses from crossing but ambulances were let through as organizers shouted "blue light" to part the crowd.

Green Party MP Caroline Lucas earlier told the BBC the group's protests could sometimes be counterproductive.

But for some people, the rallies were the only way they felt heard, she said. The government has yet to comment.

She said: "I am sorry that it has come to this and that this is the only way that people feel they can make their voices heard." 

The activists have vowed to block areas of London "for as long as possible" every day for at least a week. 

A protest in Oxford Circus on Saturday brought the West End to a standstill.

Ms. Lucas said: "Personally for example, if you are going to try and stop Tube trains moving around I think that is counterproductive.

"I think that being on the streets of London has been shown to be a way of capturing people's imaginations.

"People have joined those protests who have never protested before. They are doing it because they know we have to leave new fossil fuels in the ground.

"The International Energy Agency says that the latest IPCC (Intergovernmental Panel on Climate Change) report says that, and yet this Government and this energy strategy... is foreseeing getting out even more oil and gas from the North Sea, that is frankly immoral and the UN general secretary said that is frankly both morally and economically mad."