Confirming the slick, Sikka Range Forest Officer (RFO) B H Dave said an estimated 15 to 20 tonnes of oil must have leaked into the sea. However, a survey has been launched to find out the extent of the damage. Forest officials have picked up oil samples and sent them for tests to identify the source, he said.

The RFO said an entire mangrove forest nursery with nearly 70,000 saplings on Narara Islands in Marine National Park was destroyed while at least three other islands rich with corals were seriously affected. He said carcasses of five dolphins are lying at Narara Island. The other affected islands are Kalubhar, Goos and Munde - within the park.