A large crowd of demonstrators calling themselves Extinction Rebellion demanded slashing of new infrastructure plans linked to fossil fuels and warned about climate change at protests in the capitals of the UK and France.
Several hundred activists demonstrated in London and Paris in response to a call from an environmental movement named Extinction Rebellion to demand the immediate cessation of new infrastructure linked to fossil fuels and warn about the climate emergency.
The group blocked major roads in central Paris and London, disrupting traffic to protest "inaction" on climate change from world leaders.
Around 300 metres (980 feet) of the main thoroughfare in central Paris was taken over by activists over the Easter weekend, with some of them moving in hay bales and cement-filled containers to block traffic.
Extinction Rebellion tweeted "thousands" of protesters were "occupying" London's Marble Arch roundabout during a sit-in close to Hyde Park, demanding an end to the fossil fuel economy.
Demonstrators also glued themselves to a limousine in central London.
The Metropolitan Police said in a tweet that the protest caused "significant traffic disruption" and that the protesters "locked onto a stationary vehicle in the middle of the road... believed to be their own."
Activists from the group had glued themselves to a tanker earlier on Saturday, blocking the vehicle on a road near Hyde Park.
'End fossil filth'
Three activists including 2012 Olympic canoe slalom champion Etienne Stott climbed onto the tanker belonging to British energy giant Shell, unfurling a banner saying, "End fossil filth," Extinction Rebellion said.
"I am aware that my actions will cause anger to many people and I am prepared to be held accountable," Stott said.
"But our government should also be held to account for its decisions which are destroying our planet's ability to support human civilisation."
Six people were arrested, the Metropolitan Police said.
In Paris, activists hung out a large red banner that read: "This world is dying. Let's build the next one." The protest is scheduled to continue until Monday.
"Rebelling is our duty," had been daubed in graffiti on a wall nearby.
"This is the only way of ensuring that everyone talks a bit about climate change," Antoine, a young activist who declined to give his surname, told AFP.
A line of French riot police stood opposite the protesters, but officers did not intervene.
Anger over official policies
Extinction Rebellion has carried out a series of protests in Britain in the past week, including shutting down four of London's busiest bridges on Friday.
A scientist from the group, Emma Smart, was freed on Saturday after starting a hunger strike following her arrest earlier in the week during a protest targeting the British energy ministry, Extinction Rebellion said.
After several oil depots were targeted by the campaign group Just Stop Oil in recent days, many companies including ExxonMobil successfully took out injunctions to stop such actions, the government in London said.
The British government last week presented a new energy security strategy after the war in Ukraine and soaring inflation, with a greater focus on nuclear power and renewable energy, but also oil from the North Sea.
The strategy has angered many activists who believe the government is not doing enough to move away from fossil fuels.
Many French environmentalists have been left despondent after the first round of presidential elections last weekend in which Greens candidate Yannick Jadot and hard-left ecologist Jean-Luc Melenchon were eliminated.
A second-round run-off will be held next Sunday between centrist President Emmanuel Macron and far-right leader Marine Le Pen.