The Princess Empress was carrying 800,000l of industrial fuel oil from Bataan province, near the capital Manila, to the central province of Iloilo when its engine overheated, the Philippine coast guard said.

An initial investigation showed the “distressed” vessel drifted towards waters off Balingawan Point on Mindoro Island “due to rough sea conditions until it became half-submerged”.

The coast guard said they were monitoring a spill of diesel fuel, which had been powering the vessel, but had not found in the sea any industrial fuel oil from the ship’s cargo.

Another vessel rescued the 20 crew members on board.

The coast guard said they were in “good physical condition”.

In a separate update, the coast guard said the spill detected near the stricken vessel was 5km long and 500m wide.

An oil spill boom would be installed to control the spillage, it said.