TV star Hayden Panettiere has been involved in a violent confrontation with Japanese fishermen as she tried to disrupt their annual dolphin slaughter.

The 18-year-old actress, who stars in TV blockbuster Heroes, paddled out on a surfboard in an attempt to reach a pod of dolphins to stop them being driven into a nearby cove and killed.

But the six surfers, from Australia and the United States, were intercepted by a fishing boat before they could reach the dolphins.

The fishermen used the boat's propellers to block their way and at one point struck out with a boathook.

It was an ugly and potentially life-threatening confrontation that lasted more than 10 minutes before the surfers were forced to return to the beach.