Mauritian volunteers fished dead eels from oily waters on Tuesday as they tried to clean up damage to the Indian Ocean island's most pristine beaches after a Japanese-owned bulk carrier leaked an estimated 1,000 tonnes of oil.

The ship, MV Wakashio, owned by Nagashiki Shipping and operated by Mitsui OSK Lines Ltd, struck a coral reef on Mauritius' southeast coast on July 25 and began leaking oil last week, raising fears of a major ecological crisis.

Activists told Reuters that dead eels were floating in the water and dead starfish were marked by the sticky black liquid. Crabs and seabirds are also dying.