Tens of thousands of people demonstrated Saturday in several Swiss cities against climate change, the Swiss news agency Keystone-ATS reported.

Around 50,000 marched in all, the news agency report estimated, including 15,000 in Zurich and up to nine thousand in the capital Berne and in Lausanne.

"It's about knowing if finally we want to listen to the voice of science," high school student Jan Burckhardt told ATS.

"Save the climate please: it's the last time we ask politely," read one of the placards at the Lausanne demonstration, an AFP photographer saw.

The marches were organised by an alliance of activist groups in Switzerland, including Greenpeace, Swiss Youth for Climate and green groups.

"We don't want to stop our movement as long as our claims have not been heard, as long as we have not obtained concrete results," said Laurane Conod, one of the organisers of a smaller march in Geneva.

The climate change protests in Switzerland were in part inspired by the teenage Swedish activist Greta Thunberg, who started weekly school strikes calling for policy change on the climate issue.