Climate activists from the Elokapina protest movement - the Finnish branch of the environmental group Extinction Rebellion - blocked traffic on a main thoroughfare in Helsinki on Saturday afternoon.

Helsinki police said that prior notice of the protest on Sörnäisten rantatie was not provided by the Elokapina group, adding that there were between 40 and 50 activists involved in the protest.

Police detained 38 protestors after they refused to move to an alternative location indicated by police.

In a tweet, the protest group said that about 150 activists had been present.

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Elokapina added that the action was arranged because the Finnish government has not declared a climate and environmental emergency or reacted strongly enough to the climate and environmental crisis.

"Elokapina has closed the Sörnäisten rantatie at Kaikukatu from 3pm to show its deep disappointment with the current destructive climate policy," the group said in a press release.

Elokapina have staged a series of sit-ins and other events in the Helsinki region since October.

12.12: Updated number of detainees and other details.