The study carried out by the Wildlife Institute of India said the number of Indian tigers in the wild has more than halved compared with 2001 figures to under 1,500.
In 2001 India's tiger population was estimated at some 3,642.
Specialists say the loss of habitat and poaching were the main reasons for the continuing decline.
The government has proposed a number of urgent measures to save India's big cats from poaching.
The proposals include recruiting retired military personnel in national parks, developing ecological tourism to help locals earn a living, and moving a total of 40,000 people from some of the country's 23 tiger reserves.
A total of 1.3 billion has been allocated for the measures.
The world's tiger population is estimated at some 7,000 species with 40% living in India.
