Bangkok: Preliminary investigations by Thailand’s Department of Special Investigation has suggested carelessness by PTT Global Chemical (PTTGC) workers may have caused the large oil spill in the Gulf of Thailand last month.

The DSI is inspecting the supply line which connected a Greece-flagged tanker to a PTTGC buoy. Crude oil was being transferred from the ship to Map Ta Phut industrial estate on Rayong’s coast.

A leak in the supply line caused oil to begin spilling into the sea early on July 27, according to the DSI’s initial findings with human error deemed the most likely cause.

The DSI is looking at all possible causes and has not ruled out problems with the tanker, which was anchored nearly three nautical miles from the buoy.

A full accident review will be made available tomorrow.