Navies in the pirate-infested Gulf of Aden were put on alert on Wednesday after a Thai bulker was reportedly threatened.
The 27,700-dwt Siam Sapphire (built 1986) reported sighting a suspicious vessel or vessels in its vicinity, a knowledgeable source said.
The incident took place in the heavily-patrolled Internationally Recognised Transit Corridor (IRTC).
A helicopter from an unidentified naval vessel was dispatched to the scene but no pirate vessels were spotted.
Ship
