Anti-Koodankulam activists and a Hindu outfit supporting its commissioning clashed in Tirunelveli on Tuesday forcing an abrupt end to the fourth round of talks to break the impasse over the nuclear power plant project.

Trouble arose as Hindu Munnani activists, who had gathered at the Collectorate to present a memorandum in support of the project, came face to face with the members of People's Movement Against Nuclear Energy (PMANE).

The PMANE is spearheading the nearly five-month long stir against the project.

Police said the Hindu Munnani activists pelted stones at the vehicle in which the PMANE members arrived at the collectorate to take part in the talks between the central and state government-appointed expert committees.

Retaliating, a group of PMANE supporters attacked the Hindu Munnani workers with footwear, leading to a tense situation.

Seven Hindu Munnani volunteers, including its Vice-President V C Jayakumar, who led them, and three of PMANE were arrested, police said.

Some persons suffered "minor" injuries and some vehicles were damaged in the incident, they added.

Protesting the attack, more than 5,000 people of Idinthakarai, the epicentre of the protests against KNPP, gathered and resorted to picketing near the project site.