Shortly after 2 pm on Saturday, Helsinki police estimated that about 3,000 people had gathered at Senate Square in central Helsinki for a demonstration against Covid-19 restrictions.
Police later revised their estimate of the number of participants to 4,000.
The procession set off from Senate Square at 2.30 pm and proceeded along Pohjoisesplanadi, Mannerheimintie and Kaivokatu to Railway Square, causing traffic disruption, police said.
In a tweet soon after 3 pm, police said marchers had reached Railway Square and that traffic was returning to normal.
Law enforcement officials then upped their estimate of the number of participants, estimating that about 4,000 people took part in the procession, which took place in cold, clear weather.
Marchers bussed in from around Finland
According to a statement by the organisers, the main themes of Saturday's demonstration in Helsinki included vaccination mandates in the healthcare and social services sector, vaccinations for children and the Covid pass.
Based on the event's Facebook page, protesters were bussed to Helsinki from other parts of Finland, including Tampere, Pori, Kuopio, Kauhajoki, Seinäjoki, Lahti, Mäntsälä and Jyväskylä.
There was also a smaller demonstration in central Finland city of Jyväskylä, where police said that 450-500 people gathered on Saturday to protest against Covid restrictions.
"It went smoothly," Inspector Satu Tepponen of the Central Finland Police Department, told Yle.
Last September, an anti-restrictions protest in Helsinki drew a smaller crowd. There were also similar protests in Sweden on Saturday.