Pirates, until recently a notorious menace to international shipping in Southeast Asia, are now pursuing smaller targets, with coastal fishermen and yachtsmen increasingly at risk.

For most of the decade, armed robbery aboard ships steadily increased in a broad swathe from the Gulf of Thailand to the Sulu Sea in the southern Philippines.Thai pirate attacks were mostly against Vietnamese refugee boats, now many fewer than before, while Philippine pirates in fast motorized outriggers targeted fishermen, inter-island ferries and small freighters carrying barter goods between Malaysia and the Philippines.

But for ocean-going vessels, the prime danger has been the Malacca Straits and the narrow channels off Singapore, through which most of the East-West ocean trade is funneled.

More than 120 incidents a year were being recorded around Singapore in the mid-1980s, although shipping sources believe many other incidents went unreported. Last year only 10 attacks were reported, according to the Singapore National Shipping Association, which has led a campaign for regional cooperation to stamp out piracy.

Since 1987 Singapore, Indonesia and Malaysia have been closely cooperating with exchanges of information, increased sea patrols and sea and land searches for pirate lairs - not easy given the numerous small, heavily jungled inlets on the islands lining the shipping bottleneck.

Well over 30,000 large vessels anchor in Singapore waters each year, and there are at least 6,000 shipping movements a month through the Singapore straits.

Marine police sources say that on a pitch-dark night with a constant procession of large ships, it's hard to stop the tiny motorized sampans the raiders use to sneak up to their target.

Most of the incidents occur in the Philips Channel, 10 miles south of Singapore and used by all eastbound traffic, or near the Horsburgh Lighthouse at the exit to the South China Sea.

Loaded vessels are a prime target because their freeboard (distance from deck to waterline) is lowest, allowing pirates to draw alongside and clamber up using grappling iron sand slings.

Officials refuse to classify the raiders as pirates, insisting they are merely petty thieves out to steal cash and personal belongings with a minimum of fuss and force. They usually don't carry guns, unlike the pirates operating around the coast of West Africa, for example.

"They're more of a nuisance than anything else," says Kong Leong, director of the Singapore Marine Department. "The amounts involved are minimal and there is no loss of cargo or delay in the ship's timetable."

Because of this, many ship's masters don't bother to report the attacks until they reach their destination, if at all. But occasionally attacks turn nasty.

Last November a crewman on the Indonesian-bound freighter Hai Hui was going to rouse the master early one morning when he spotted about a dozen armed men on the deck. He ran back to the bridge to raise the alarm. But when the ship's lights were switched on, the raiders had vanished - along with the master, Tsui Hung Ting, 55, of Hong Kong. He hasn't been seen since.

Only two weeks earlier, the Nedlloyd Manila had to return to port after its master was seriously injured with a "parange" (machete) slash wound to the head when he tried to fight off robbers who burst into his cabin.

Shipowners have begun adopting counter-measures. The most obvious is to traverse the channels in daylight. But if this isn't possible, masters are told to light their vessels, maintain extra night watches and keep personal accommodations locked. A few shipping lines tell their crews not to fight for the loss of a few personal possessions, but others have issued their vessels with high-pressure water hoses and even stun guns to ward off attackers.

With ocean-going ships more on their guard, would-be pirates appear to be turning their attention to softer targets - fishermen operating among Singapore's southern islands. The pattern is always the same: an isolated boat with perhaps only one man on board; a motorized sampan suddenly looms out of the dark, men armed with parangs leap on board, strip the fisherman of any personal belongings, plus his outboard motor if he has one, and disappear into the night.

No figures have been compiled on such attacks, but they are regularly reported in the local press. Many lone anglers now try to fish in groups for protection, while others have begun carrying knives to fight back.

Officials say many foreign yatchsmen now carry more substantial weapons as they pass through Southeast Asian waters, including grenade-launchers and automatic weapons.