Indian fishermen and anti-nuclear activists on Saturday mounted a sea protest against an atomic power plant following violent demonstrations earlier this month, police said.

Some 3,000 fishermen and anti-nuclear activists in 500 fishing boats sought to block a port in southern Tamil Nadu state to protest against the loading of uranium at the under-construction power plant, police said.

Tuticorin port spokesman V. Satyarajan described the protest as "peaceful" and said there was no disruption to traffic at the port from the attempted blockade off Tuticorin town, 100 kilometres (62 miles) from the project.

Witnesses said the boat-borne protesters shouted anti-nuclear slogans and demanded an end to the loading of uranium at the Russian-backed project.

"We will continue to protest until the nuclear plant is shut down," said Subash Fernando, one of the leaders of the sea protest.

On land, demonstrators from villages near the plant formed a human chain in Tuticorin to protest against the loading of the fuel rods.

Earlier this month, one fisherman was shot dead by police as hundreds of protesters clashed with armed officers.

Last week, India's Supreme Court denied a request to suspend the loading of the rods at the plant which opponents say poses a danger to local people.

The demonstrations have broken a six-month lull in protests against the power station, one of many India hopes to build as part of its goal to produce 63,000 megawatts of nuclear power by 2032 -- a near 14-fold rise from current levels.

India's existing 20 nuclear reactors now generate just 4,780 megawatts.

Authorities say the first of the two units of the much-delayed project in the Koodankulam region is ready for operation.

Since last year's quake-tsunami in Japan sparked a crisis at the Fukushima plant, activists have also campaigned to stop work from beginning at Jaitapur in Maharashtra state on what would be one of the world's biggest nuclear facilities.