Shortly after 2am three perpetrators boarded the 179,227-dwt Densa Shark (built 2012) armed with knives.

They were sighted in the engine room but left the Marinsa Denizcilik-owned bulker without taking anything.

Two and a half hours later, a group of five entered the engine room of the 84,000-cbm Clipper Posh (built 2013) but nothing was missing after they left.

Edvin Endresen, chief executive of Solvang which owns the vessel, confirms the incident to TradeWinds and says the ship is now preparing to depart after a comprehensive search was conducted.

At around 5.30am, five raiders were again seen in the engine room of the 105,348-dwt Pro Triumph (built 2009).

The attackers tied up the chief and first engineer of the SK Shipping-owned ship and stole some generator spares parts.

They fled when the alarm was raised.

All three incidents took place in close proximity to each other, within four to 10 nautical miles.

Could be the same group

ReCAAP of Singapore said the perpetrators could possibly be from the same group given the close interval of time and distance between the incidents.

But it added this cannot be confirmed.

ReCAAP said the thefts were targeting engine spare parts as all of them involved engine rooms.