Up to 25,000 people marched through Paris on Saturday urging greater action on climate change, despite fears that their protest would be scuppered by "yellow vest" demonstrations.
Police estimated the number of green activists heading onto the streets at 17,000 while organisers counted 25,000 urging world governments to better protect the environment.
The numbers were similar to previous climate marches in Paris, despite sporadic violence in the city on Saturday among thousands of "yellow vest" demonstrators who want more help for France's poor.
Organisers had to change the route of the climate march, marching instead from Place de la Nation to Place de la Republique, due to the yellow vest demonstrations, but refused a request by Interior Minister Christophe Castaner to postpone it.
"It was unthinkable to cancel this march. It's important to talk about problems related to the end of the world as well as the end of the month," Elodie Nace, a spokeswoman for green NGO Alternatiba, told the crowds.
Thousands also marched in other French cities, including an estimated 10,000 in Marseille, 3,500 in Montpellier and 3,000 in Lille.
The "yellow vest" movement has been spurred by anger in small-town and rural France at rising car fuel taxes which were aimed at helping the country transition to a greener economy, but which protesters say hurts the poor.
But green activists at the climate marches urged people to find solutions for both environmental problems and the financial struggles of France's poorest.
"Yellow vests, green vests -- same anger," they chanted.
Some "yellow vest" activists, clad in their emblematic high-visibility road jackets, joined the Paris march after breaking off from their own demonstration.
Marches had been organised in more than 120 towns across France to mark the COP24 climate talks in Poland.