The Singapore navy says it has information that an unknown terrorist group is preparing attacks on oil tankers in the Strait of Malacca. Vessels are being advised to tighten up security measures on board.

The navy adds that other large ships carrying hazardous cargoes may also be at risk. The navies of Singapore, Indonesia and Malaysia have commenced precautionary patrols. 

The Malacca Strait, between Malaysia and the Indonesian island Sumatra, is a busy sea lane infested with pirates. In their fast, easily manoeuvrable boats, pirates particularly target large ships which are forced to slow down when entering the narrow channel.

Any closure of the Malacca Strait following an attack on a ship could have far-reaching consequences for world trade; Singapore is the busiest container port in the world, and many ships also stop there to take on fuel.