KOLKATA: Indian authorities were on alert on Saturday after a Bangladeshi tanker sank and dumped thousands of litres of oil into rivers of the Sundarbans, the world’s largest mangrove forest.

The tanker collided with an empty cargo vessel on Tuesday on the Bangladeshi side, spilling the oil into the protected area, which straddles India and Bangladesh and is home to rare Irrawaddy and Ganges dolphins.

Bangladeshis were attempting a big clean-up after environmentalists warned of an ecological “catastrophe” at the UNESCO World Heritage site where famed Bengal Royal Tigers roam.

On the Indian side, Pradip Vyas, director of the Sunderbans Biosphere, said: “There are no reports till now that the oil spill has reached the Indian part of the Sunderbans”. But Indian “wildlife officials have been deployed along the Sunderbans area bordering Bangladesh to check if the spill is spreading” as a precaution, he said.

Bangladeshi villagers have been using sponges, shovels and even spoons to clean up the huge oil spill which has spread to a second river and a network of canals.

The oil has already spread over an 80-kilometre area.

Rescue vessels salvaged on Thursday the OT Southern Star 7 oil, which was carrying some 357,000 litres of oil when it sank in the Shela river.

Rubayat Mansur, Bangladesh head of the New York-based Wildlife Conservation Society, who visited the trawler, said most of the oil seemed to have leaked out before it was salvaged and “only few hundred litres” of oil remained inside.

Local residents on the Bangladesh side reported seeing dead otters near river banks.

The Sundarbans forest sprawls over 10,000 square kilometres.

Published in Dawn, December 14th, 2014