Photos: 39 dolphins, 3 whales wash up on Mauritius after oil spill

The number of dead dolphins that have washed ashore on the Indian Ocean island nation of Mauritius after an oil spill has risen to 39, the government said Friday, ahead of protests this weekend against authorities' handling of the disaster at sea.

Three whales also were found dead, an environmental expert said. It's not yet clear what caused the dolphins' deaths, but alarmed environmentalists have called for an investigation.

The dolphins began washing up this week, several days after some 1,000 tons of fuel spilled from a Japanese ship that ran aground on a coral reef then split apart under the pounding surf. | Above: Workers load carcasses of dolphins that were washed up on shore at the Grand Sable, Mauritius.

The country's fisheries minister, Sudheer Maudhoo, told reporters that some dead dolphins had injuries but he denied reports that oil had been found inside them and called their deaths a "sad coincidence." Experts were still studying the corpses.

A boy touches the carcass of melon-headed whale at the beach in Grand Sable, Mauritius

Workers load carcasses of dolphins that were washed up

Workers load carcasses of dolphins that were washed up on shore at the Grand Sable

A dead dolphin is seen on a boat as it is brought to the marine fish farm of Mahebourg, Mauritius

A general view shows the bulk carrier ship MV Wakashio, that ran aground on a reef, at Riviere des Creoles, Mauritius

Men recover the carcass of melon-headed whale at the beach in Grand Sable

Dolphins are seen as they swim near the shore of the Indian Ocean near Pointe aux Feuilles, Mauritius

Coast guards bring dead dolphins to the marine fish farm of Mahebourg, Mauritius

A policeman takes a photograph of a carcass of a dolphin that was washed up on shore at the Grand Sable