The recent spate of pirate attacks off Southeast Asian waters has stoke fears that vital shipping lanes are again threatened by high-sea crimes.

Malaysia’s piracy reporting centre International Maritime Bureau (IMB) is warning small tankers to maintain strict anti-piracy measures in the South China Sea as at least six known cases of attacks have been reported since April this year.

The latest hijackings seem to follow a specific modus operandi, where armed pirates seize a small tanker and siphon off its cargo to large bunker tankers or other small tankers in a ship-to-ship operation. In some cases navigational equipment is destroyed but the crew are left unhurt. They then release the hijacked vessels.

“These types of incidents are not common in this region which makes the situation even more alarming,” said IMB.

“The pirates appear to be interested in oil products such as diesel oil. One of the hijacked tankers was released quickly possibly because the pirates realised it had the wrong type of cargo,” IMB noted.

IMB has issued a warning to all ships that these attacks have occurred against small coastal tankers primarily in the South China Sea waters off Bintan and Bintulu islands.