Kolkata, Aug. 20 -- The Sundarbans Tiger Reserve (STR) in South 24 Parganas, a UNESCO heritage site, is set to become India's second-largest tiger reserve after the Union government cleared a proposal by West Bengal to include three ranges in the state's southernmost district, official sources said.

The South 24 Parganas, the state's biggest district with an area of 9960 km and home of the Sundarbans with the world's largest mangrove forest, is located in the delta where the Ganges, Brahmaputra, and Meghna rivers meet the Bay of Bengal. It spans across India and Bangladesh, also home of the Royal Bengal Tigers (RBTs).

The latest tiger census said the Sundarbans has about 101 tigers, of them 80 inside the Sundarbans Tiger Reserve and 21 in...