Preliminary investigations by Singapore authorities into reports that tainted fuel had been sold to several ships found that Glencore supplied the fuel.

Glencore Singapore Pte informed the Maritime Port Authority that, on receiving reports of its fuel being contaminated, the company tested its blended product and found that one sourced from overseas was tainted. At the time of testing, Glencore had sold part of the affected fuel to PetroChina Co., which then supplied ships in Singapore, the MPA said in a statement Wednesday.

Glencore and PetroChina have supplied the affected fuel to about 200 ships in the Port of Singapore to date, authorities said. Of these, about 80 ships have reported various issues with their fuel pumps and engines. 

Singapore is the largest marine fuel supplier in the world and sits at the crossroads of a centuries-old trade route that links Asia to Europe, the Middle East, and the U.S. Gulf Coast. Bloomberg reported earlier this month that a growing number of ships that received contaminated marine fuel at the major hub of Singapore have suffered power blackouts, citing fuel testing firm Veritas Petroleum Services.

Ships losing power at sea can be extremely dangerous, increasing the risk of collision or running aground. In 2018, numerous vessels suffered serious technical problems and mechanical damages after receiving contaminated fuel initially supplied in Houston.

Bunker fuel supplied in the Port of Singapore must meet the international standards of petroleum products of fuel and the contaminated fuel purchased by Glencore was in compliance with those guidelines, according to the statement. The MPA said it’s currently in talks with the industry on additional fuel quality checks that would screen for unacceptable chemicals.