Malaysia's Coast Guard said on Saturday one of two large oil tanks involved in an accident that resulted in fires on both vessels had left the scene of the accident. It was also believed that the tracking system of that tanker had been turned off.

The coastguard said that it was tracking the location of the Sao Tome & Principe flagged tanker Ceres I which was suspected to have been within Malaysian waterways.

The Maritime and Port Authority of Singapore said that the Ceres I had been involved in a collision early Friday morning with the Hafnia Nile, a vessel flying the Singapore flag. This occurred about 55 km (35miles) northeast of Pedra Branca on the Singaporean Island.

The MPA reported that all 40 crew members on board the Ceres I had been accounted for. 14 of them had been evacuated via helicopter by the Singapore Air Force, while the remaining 26 were engaged in firefighting onboard.

No comment could be obtained from the Chinese owner of Ceres 1.

The Ceres I supertanker is a very-large crude carrier (VLCC). Ship tracking data showed that it was last carrying 2 million barrels Iranian crude.

The Iranian oil ministry stated on Saturday, however, that neither vessel had carried Iranian crude.

Michelle Wiese Bockmann said that the area where Ceres I was anchored has been used by dark fleet vessels to transfer Iranian oil, in violation of U.S. sanction, she added.

Matt Stanley, Kpler's head of EMEA & APAC market engagement, stated on Friday that Ceres I had "gone dark" several times. He was referring to the instances when vessels turn off their AIS transponders.

The 74,000-deadweight-tons capacity Panamax tanker Hafnia Nile was carrying about 300,000 barrels of naphtha, according to ship-tracking data from Kpler and LSEG.

The Hafnia Nile was evacuated on Friday and all 22 crew members arrived in Singapore. The Malaysian Coast Guard posted a video on Saturday showing the Hafnia Nile floating. Singapore's MPA failed to respond immediately on Saturday when asked for comment.

Hafnia, the operator of the tanker, said that salvage experts had boarded the Hafnia Nile to establish a connection with one tug.

Hafnia stated that "a first assessment confirms there are no visible fires on board the vessel." Pollution levels are not yet known around the vessel.

It added that discussions are in progress with Malaysian authorities regarding the safe movement of the tanker. Hafnia said that it was also working with Singapore to investigate the cause of the accident.

Singapore is Asia's most important oil trading hub, and the largest bunkering facility in the world. The waters surrounding Singapore are some of the busiest sea lanes in the world. Reporting by Danial Azar in Kuala Lumpur, and Florence Tan, in Singapore. Writing by Tony Munroe. Editing by William Mallard. Tomasz Janowski, Alexandra Hudson.