Coal mining for electricity generation is the biggest threat to India's tigers, a report by environmental activists Greenpeace warned, demanding a moratorium on clearances for new mines just days after massive blackouts highlighted power shortages.

A hot-button issue in India, tiger conservation pits the need to preserve wildlife against the development needs of a country that witnessed the slowest economic growth in nine years in March and where hundreds of millions continue to live below poverty line.

India is home to more than half of the world's tigers, with 1,706 living in the wild, compared to 100,000 at the turn of the last century.

The emerging Asian power has witnessed an unprecedented hike in new coal mines and coal-run power plants in the past five years, placing the lives of many endangered animals at risk, the report released late on Wednesday said.

Calling the situation stark, Greenpeace says coal mining has already started affecting tigers in many areas such as Chandrapur in the state of Maharashtra.

But there are other locations where the problem is already, or will soon be, equally severe, Greenpeace campaigner Ashish Fernandes told Reuters.

Reeling from the two blackouts this week and an ongoing shortage of power, the Indian government is under great pressure to mine more coal to meet a soaring demand for energy.

Frequent power outages are seen as a major constraint to faster economic growth, putting pressure on the government to permit the development of coal mines.

India sits on the world's fifth-largest coal reserves, and produces the most after China and the United States.

The report says if India continues its dependence on coal to meet its energy needs, the destruction already seen in these areas will multiply across much of central India, which has 80 percent of the country's coal reserves and 35 per cent of its tigers.

Last month, in a move to protect the endangered cats, the Supreme Court in India ordered a ban on tourism in core zones of more than 40 of the country's tiger reserves.

The government has for decades been fighting a losing battle to conserve tiger numbers against poaching, which feeds a lucrative cross-border trade in body parts, and the loss of natural habitat.