Pirates armed with guns and knives stormed a diving ship crewed by New Zealanders and other nationals in the notoriously dangerous Malacca Straits.
The pirates boarded the deep-sea diving support vessel Ocean Winsertor, robbed crew members of cash and valuables and escaped.
The ship, crewed by New Zealanders, Australians, Malaysians, Indonesians and
others, was 160km from Singapore near the Lingga Islands, southwest of Bintan and Batam, when the pirates struck.
It had been heading to Singapore after a three-week diving trip in East Timor.
About half the crew of 50 were asleep when the pirates, wearing ski masks, boarded the ship from two small boats. They fired a warning shot, cut the communication wires and then held the crew at gunpoint.
One crew member had a rope tied around his neck and another was hit on the head with a bar. No one else was injured.
The pirates were looking to rob the safe in the captain's cabin, but it was empty, Singapore's Straits Times newspaper said.
"A lot of us thought that was it," a diver in his 30s was quoted as saying. "We didn't know whether they would kill us."
The pirates were reported to have fled with several laptop computers, mobile phones and thousands of dollars in cash.
The ship arrived at the Loyang Offshore Supply base and is scheduled to sail for Thailand today.
The 900km Strait of Malacca is a notoriously high-risk area for pirate attacks, according to the International Maritime Bureau.
Usually container ships are the targets in the straits, which form a narrow corridor between ports in East Asia, Europe and the Middle East - and one of the main shipping routes for New Zealand goods.
International Maritime Bureau's Noel Choong said the maritime industry was extremely concerned about such attacks. "We call upon the Indonesian Government to step up patrols in these hotspots," he said.
When the IMB issued a warning this year at least one New Zealand shipping firm boosted security and warned staff about the dangers of the straits.
There were 28 pirate attacks in the first three months of this year.
No other region had more than nine attacks.
The latest act is the first time a New Zealand sailor has been listed as robbed by pirates in the area.
The Malaysian Navy said last week it would provide escorts to commercial ships travelling through its waters if the risk of a pirate or terrorist attack was deemed high.
