Experts suggest that Singapore's stringent bunker standards give fuel coming from the city-state a higher resale value in illegal markets.
Higher bunker standards in Singapore may be inadvertently causing ships departing from the city-state to be targeted by pirates, suggests Singaporean media.
Bunkers are considered the "the perfect product to steal" because they are "nearly untraceable," according to Karsten von Hoesslin, special projects manager of Risk Intelligence.
Data from the Regional Cooperation Agreement on Combating Piracy and Armed Robbery against Ships in Asia (ReCAAP) shows eight of the 12 successful bunker thefts reported in Asia last year involved ships with Singapore as their last port of call.
Nicholas Teo, Deputy Director, ReCAAP
More vessels departing from Singapore seem to be boarded
"There is no clear evidence that Singapore-registered vessels are targeted, but more vessels departing from Singapore seem to be boarded," said ReCAAP deputy director Nicholas Teo.
One theory as to why vessels departing Singapore are targeted more frequently is that better quality bunkers fetch higher prices on the illegal resale market.
Maritime security analysts also theorize that the larger share of vessels departing from Singapore could be due to the large amount of traffic the port sees, in addition to higher rates of incident reporting.
According to von Hoesslin, while bunker pirate "foot soldiers" tend to be Indonesian, the "middlemen and big bosses" were said to be "generally Malaysian and Singaporean."
"The money often ends up in a 'Big Boss' Singaporean bank account," he added.
"Syndicates have acknowledged that bunkering agents in Singapore are often the 'insider information' link that is compromised when it comes to the security of the vessel and cargo."
Sam Bateman, adviser to the Maritime Security Programme at the S. Rajaratnam School of International Studies
There are so many of these small product tankers around the region, I suspect that inspection and security regimes for these ships are not quite as strict as those for larger vessels
Hijackings are expected to continue given that the illegal bunker market is lucrative, especially in countries such as Indonesia where bunker distribution issues exist, according to Sam Bateman, an expert affiliated with Singapore's S. Rajaratnam School of International Studies.
"What we have here in South-east Asia is pure property theft, in which seafarers are unwittingly being put in harm's way, with several killed," said Phillip Belcher, marine director of the International Association of Independent Tanker Owners (INTERTANKO).
"It's a commercial operation... but seafarers are getting in the way, suffering fatal injuries."
Bateman also noted that the sheer number of players operating in the region made it herder to combat the problem.
"There are so many of these small product tankers around the region, I suspect that inspection and security regimes for these ships are not quite as strict as those for larger vessels," he said.
"Closer co-operation is required between all regional maritime and law-enforcement agencies, including shore police forces and Customs agencies - recognising that the siphoned-off fuel has to be brought ashore somewhere."
Earlier this week, Singapore-based Ocean Tankers announced that it would be increasing anti-piracy measures after two separate hijackings that took place less than eight months apart.