Police periodically dispersed crowds, who chanted and held placards, but did not stop the event from taking place, though there is an anti-pandemic ban on gatherings larger than 10 people.

The protesters who were shaved were draped in protective sheets emblazoned with messages condemning the Japanese plan and calling for it to be ditched.

One read: “The Japanese government should immediately cancel the plan to release the contaminated water.”

Japan’s government said last week it will release more than 1 million tonnes of treated water from the Fukushima site in stages starting in about two years.

Seoul has strongly rebuked the decision, with the foreign ministry summoning the Japanese ambassador and President Moon Jae-in ordering officials to explore petitioning an international court.

US climate envoy John Kerry on Sunday said he believed Japan had made the decision in a transparent manner and would continue to follow due procedures.