Pirates in the Malacca Strait have attacked two UN-chartered ships and threatened a Japanese cargo carrier, a maritime watchdog has said.Except for minor incidents, the Strait of Malacca has been without pirate attacks for several months.
The UN ships were set for Indonesia's Aceh province when they were attacked on Sunday, said Noel Choong of the International Maritime Bureau.
The pirates stole some cash and construction materials belonging to the UN's World Food Programme.
The Japanese ship's crew repulsed an attack on Tuesday.
A crew member noticed an unlit speedboat approaching.
"They used high-pressure fire hoses and floodlights on the pirate's boat to scare them off, but the pirates, believed to be armed with guns, still chased them for about five minutes before vanishing," Mr Choong told Kyodo news agency.
No injuries were reported in the incidents, but they raised fears of a resurgence of piracy in the area.