Pirates with automatic weapons and cell phones have brought a terrifying sophistication to old-fashioned buccaneering in the shipping lanes of Asia, in some cases even killing entire ships' crews.

"We thought pirates belonged to history, but they are back and meaner than ever," said Yoshihiko Yamada, of the Nippon Foundation, a private Japanese group that tracks piracy and that next week will host a conference for ship owners to discuss ways to combat it.

The case of the Japanese freighter Tenyu illustrates the new high-tech, high-finance face of piracy. The 277-foot vessel steamed out of Indonesia last September loaded with $3 million worth of aluminum ingots bound for South Korea. The ship's owners lost radio contact with it the next day.

Three months later, the Tenyu turned up at a seedy Chinese port with a new name freshly painted on its bow -- its fourth name since it disappeared, it turned out -- a new Indonesian crew and a cargo of palm oil. The 14 original crew members are presumed dead, and investigators say the aluminum ingots were unloaded and sold in Burma, ultimately bound for Chinese buyers.

East Asia has always had piracy, but the number of cases has increased dramatically in recent years, especially since the region's economy went into a tailspin two years ago. Historically, Yamada said, economic or political instability in the Far East has led to violence and thuggery at sea. Last year, 59 cases of piracy -- almost a third of the 192 reported worldwide -- occurred off the coast of Indonesia, the country hit hardest by the Asian economic crisis.

Estimates of financial losses due to acts of piracy around the world have reached as high as $16 billion a year, with the vast majority occurring in Asia, according to the London-based International Maritime Bureau, which maintains a Piracy Reporting Center in Malaysia. In a recent report, the bureau cautioned against "romanticized" views of pirates as Robin Hood figures and "bearded renegades sailing seas of endless blue." The truth, it said, "is that modern day piracy . . . is a violent, bloody, ruthless practice and is made the more fearsome by the knowledge on the part of the victims that they are alone and defenseless."

Officials who track international piracy say the rate of violence accompanying ship takeovers is increasing at an alarming rate. Pirates killed at least 67 seamen last year -- all but one of them in Asia -- and nearly 40 more are unaccounted for. Yamada estimated that on average worldwide, pirates attack a ship a day and kill a seaman a week.

The number of wholesale killings of crews is increasing as well. In addition to the Tenyu case, all 23 crewmen of the Hong Kong freighter Cheung Son were reportedly lined up on deck and gunned down by pirates who hijacked the ship off China in December. Six bodies -- weighted, bound and gagged -- showed up in fishermen's nets. The 450-foot ship, loaded with iron ore, is still missing. Another 39 crewmen are missing from two other cargo ships that disappeared without a trace off Hong Kong in December.

Investigators are confounded by modern pirate syndicates that resemble international business conglomerates, with branches and employees across the region. Maritime experts say the Tenyu case involved South Korean planners, Indonesian thugs, Burmese dock-hands and black marketeers, and at least some confederates in China -- all part of a network that authorities still have not fully uncovered.

Modern pirates still use centuries-old techniques. They usually sneak up on a vessel at night, throw a hook over the stern and climb aboard. But these days, they are aided in their crimes by high-powered businessmen who invest heavily in the latest technology. One pirate ship captured recently in Indonesia was outfitted with bogus immigration stamps, tools to forge ship documents and sophisticated radar, communications and satellite-tracking equipment.

In some cases, the pirates operate like an attacking fleet. In March, the 5,600-ton freighter Marine Master, loaded with soda ash -- used in the production of glass, soap and paper -- was attacked off Thailand by 20 pirates in three boats. All the pirates were armed with automatic rifles or pistols, and some wore military uniforms and ski masks. They shot and wounded one crew member, then set all 16 crewmen adrift in flimsy plastic life rafts. They were rescued by fishermen six days later, but the ship and its cargo are still missing.

Authorities say they see little prospect that piracy can be stopped altogether. The high seas have always been a thief's dream, especially in places like the Strait of Malacca, the narrow seaway separating Indonesia from Thailand, Malaysia and Singapore. The Tenyu was hijacked in that tight passage, the maritime version of a dark alley, where ships must slow down to navigate safely -- offering a perfect opening to pirates.

Law enforcement agencies in different countries are often stymied by crimes that occur in waters claimed by several countries, or in international waters. And many ship owners do not bother to report instances of piracy, knowing that every day their vessel is idled for an investigation costs them tens of thousands of dollars in lost revenue, compounding their original loss.

Many authorities in Asia say that some countries, particularly China, appear to allow piracy to flourish. They note that in several cases, pirates have sailed stolen ships to China, unloaded and sold the cargo and then walked away without interruption by authorities. Officials in Beijing have denied such allegations, but suspicions persist that corrupt local officials, especially former military officials, view piracy as a lucrative side business.

Organizations such as the Nippon Foundation say the best way to fight piracy is prevention -- through better organization among ship owners. They are advising that ships be outfitted with high-tech alarms, motion detectors, laser sensors and water cannons. They are also urging ship owners to install hidden transmitters to help locate hijacked ships.

"The best prevention is an old one," Yamada said. "Keep a good lookout."