India's largest nuclear plant -- dogged by protests and multiple delays -- is generating power and was linked Tuesday to the grid in the country's south, an official said.

The Russian-backed Kudankulam plant is designed to help meet surging demand for electricity in Asia's third-largest economy where blackouts are frequent.

Unit one of the Kudankulam Nuclear Power Plant in the state of Tamil Nadu was "synchronised with the power grid" and "is generating 160 megawatts", R.S. Sundar, site director of the state-run Nuclear Power Corp of India, said in a statement.

"The power will be further raised to 500 mw, 750 mw and 1,000 mw in stages," he added, as the plant clears various tests.

The reactor's commissioning came after Prime Minister Manmohan Singh failed Monday to strike a nuclear power deal with Russia in Moscow over the Kudankulam project. Agreement has been held up by India's strict safety liability law.

Work has been completed on the 1,000-megawatt first unit and is nearly finished on a second 1,000-mw reactor, despite local protests that delayed construction.

Singh had been hoping to strike deals for an additional two Russian-backed reactors at the same location as India looks to meet surging electricity demand.

But Japan's 2011 Fukushima nuclear power plant accident prompted India to adopt a strict safety liability law, which Russia argues should not be applied to the project since it was conceived many years before the legislation came into existence.

Russia and India issued a joint statement during Singh's visit saying they had "agreed to speed up work on drafting a general framework agreement" on the third and fourth planned reactors at Kudankulam and would seek to "resolve all outstanding issues".

India's liability law says nuclear firms planning to build plants in India must pay large sums in the event of an accident.

Other nuclear power plant suppliers have also expressed strong reservations over the law.

Plans for the Kudankulam facility were first drawn up in 1988. It was supposed to open in 2011 but large, often violent protests, by residents worried about the possibility of a nuclear accident delayed the startup.

Opponents of the plant, on the coast devastated by the 2004 Asian tsunami, say it is located in a seismically sensitive area and fear a Fukushima-style disaster could kill thousands.

The plant is one of many 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.

Once the first unit of the Kudankulam plant is fully onstream, the nuclear power contribution to the country's energy supply will increase to 5,789 MW.

The plant is the 20th nuclear power station connected to India's power grid.

The Kudankulam nuclear plant project attained "criticality" -- the point when a nuclear chain reaction becomes self-sustaining -- in July.

The second reactor is expected to be brought into service by mid-2014.