Climate activists from the Elokapina protest movement — the Finnish branch of the environmental group Extinction Rebellion — blocked Mannerheimintie in downtown Helsinki on Thursday evening.
In a statement, Helsinki police said they respect and will secure protesters' freedom of expression, but informed the activists in advance that Mannerheimintie is not a suitable place to organise a demonstration.
The police statement added that the protest may cause significant disruption to traffic in the area, and that they are also prepared for the possibility of counter-demonstrations.
If the police deem that the demonstration endangers public order and safety or obstructs traffic, officers will intervene, they said.
The protestors are carrying placards that call for an end to deforestation, among other demands.
Elokapina held a similar protest on Mannerheimintie — one of the capital's main thoroughfares — last May, which involved about 500 activists.
The group has called on Finland's government to declare a climate and environmental emergency, and to create binding legislation that will achieve carbon neutrality by 2025, a decade ahead of the government's current goal of 2035.
Would you like a roundup of the week's top stories in your inbox every Thursday? Then sign up to receive our weekly email!