The Princess Empress was travelling from Bataan province, near the capital Manila, to the central province of Iloilo on Tuesday when it had engine trouble and sank in rough seas off Oriental Mindoro province.

The Philippine coast guard initially reported the spillage was diesel fuel, which had been powering the vessel, and not industrial fuel oil from the ship’s cargo.

But water sample test results showed some of the cargo had also leaked into waters off Naujan municipality, the coast guard said today, sparking concern for the region’s rich marine life and coral reefs.

The spill had spread over 24sq km of water by yesterday, coast guard said previously.

It is not known how much diesel fuel and industrial fuel oil is in the water.

Provincial governor Humerlito Dolor said a search was still underway for the stricken tanker, estimated to be 460m below sea level, and stop it leaking.

“The coast guard made assurances to us that they are ready to syphon off the oil once they identify (the location),” Dolor told local media.

“Unfortunately, after two aerial surveillance (flights) we still can’t find the exact location of the ship.”

In the meantime, the coast guard has deployed oil spill booms to try to contain the material and sprayed chemicals to break down the oil.

Fishermen and tourism operators along the coast depend heavily on the waters for their livelihoods and there are concerns these could be at risk.

Oil has been spotted along a roughly 60km stretch of water between Naujan and Bongabong municipality, said Ram Temena, Oriental Mindoro disaster operations chief.

“We have many fish sanctuaries along the coast,” Temena said.

“It could have a huge impact due to the possibility that the oil could attach to the coral reefs, affecting the marine biodiversity.”

Some spillage has washed up on the shores of at least two villages in Naujan and one in Pola municipality.

Resort worker Andrea Riva said she and her colleagues were “keeping our fingers crossed” that the waves did not bring the spillage to the waters off Pinamalayan municipality, south of Pola.

Bongabong municipal disaster officer Michael Fanoga said fishermen had complained of a “foul smell” about 2km offshore.

“If it spreads in the shoreline, our beaches will be destroyed as well as the remaining coral,” Fanoga said.