The Climate March was held in Madrid in connection with the international climate conference COP25. It was attended by Swedish teen eco-activist Greta Thunberg and representatives of environmental organisations Greenpeace, Alliance for Climate, 2020 Rise For Climate, and Fridays For Future.
"Today we are talking about a march for climate # 6DPorElClima, in which more than 500,000 people took to the streets", Ecologists in Action wrote on Twitter.
According to the Spanish National Police, the number of participants was 15,000, which is 30 times less than that claimed by organisers.
Greta Thunberg arrived in Madrid by night train from Lisbon, where she arrived on Tuesday from the United States with her father in a private catamaran Vagabonde.
The UN Climate Change Conference COP25 is being held in Madrid from 2 to 13 December and is chaired by Chile. Representatives of almost 200 countries are taking part in it and about 30,000 people have been accredited to the event.