A bomb blast near India's biggest nuclear power plant killed six people, police said Wednesday, sparking a probe into whether the explosion was linked to protests against the facility.

The home-made bomb accidentally exploded overnight in a village near Kudankulam power plant in the southern state of Tamil Nadu, destroying three homes and causing injuries, the district police chief told AFP.

"The bomb exploded accidently inside a house. Six people died and three more are seriously injured," police superintendant Vijayendra Bidari said.

"Some anti-nuclear activists were living in this village. This house was being used as a bomb-making facility. We are investigating from all angles," he said.

The coastal village is some four kilometres (2.4 miles) from the Russian-built plant which opened in October after delays and often violent protests by locals fearing a radiation leak.

A senior official at the Department of Atomic Energy said the plant was safe and functioning normally, the Press Trust of India said.

Television footage showed at least three homes collapsed from the force of the blast in Idinagarai Tsunami colony, part of Idinthakarai village, from where most of the protests in recent years have stemmed.

The People's Movement Against Nuclear Energy, which has been spearheading protests against the plant, denied its supporters were involved in the explosion, local media reports said.

Some residents were stockpiling small, crude bombs because they were embroiled in a feud with others in the village, according to the Times of India. The bomb exploded while the villagers were assembling it.

Opponents of the plant, located on the coast devastated by the 2004 Asian tsunami, say it is built in a seismically sensitive area and are concerned about a Fukushima-style disaster.

The plant -- the plans for which were first drawn up in 1988 -- is designed to help meet a surging demand for electricity in Asia's third-largest economy where power blackouts are frequent.

It is one of many that India hopes to build as part of its aim of generating 63,000 megawatts of nuclear power by 2030 -- part of a planned near 15-fold rise from current levels, according to the Nuclear Power Corp.

The project attained "criticality" -- the point when a nuclear chain reaction becomes self-sustaining -- in July and started pumping electricity months later.