The first passport the man produced was Canadian, in the name of Sammy Abitbol. But when the immigration officer at the border station on Interstate 87 in New York discovered that Abitol's TransAm was registered to a "Tayssier Danhash," he decided to run both names through his computer.

The crime files showed that Abitbol's record was clean. But Danhash's name lit up the screen. He was wanted for passport fraud in the United States, had been deported from England, Australia and Germany and was facing inquiries from Argentina about charges of document fraud.

By the time inspectors had found files with photos and fingerprints confirming that Abitol was indeed Danhash, he had hidden two more passports in his underwear. He also had a Massachusetts driver's license in the name of Philip Marlais Davies and a .44 magnum pistol hidden in the engine compartment of his car.

This man of many passports, who pleaded guilty to federal passport fraud charges earlier this year, exemplifies a growing problem for officials at border crossings around the world.

Phony travel documents, a byproduct of international problems ranging from civil war to terrorism, are becoming more sophisticated and more difficult to detect. In addition, according to experts from the State and Justice departments, they are being manufactured and distributed in a more organized fashion than ever.

"A passport can be reported lost or stolen in one part of the world and resurface in another six months later," said Louis N. Deaner of the State Department's Special Operations Division. "We've had passports lost or stolen in Europe resurfacing in Asia."

"A passport isn't an end in itself, it's a means to a further end," he added. The most common motive -- accounting for at least half of forged U.S. passports -- is illegal immigration to the United States, Deaner said.

Worldwide, document vendors trafficking in fraudulent identity documents service the top echelon of criminal industries, such as drug smugglers and organized crime, as well as a minor-league rogues' gallery of bad-check artists, tax evaders and assorted unsavory border-jumpers, experts say.

"A big problem now is terrorist groups," said a Justice Department official. "They want passports to facilitate the cashing of large amounts of traveler's checks as well as for increased freedom of movement. They will steal blank passports in bulk from European countries and the Far East. We get reports of that sort of thing four or five times a month."

But although the clientele for the underground document vendors changes little over the years, Deaner said the manufacturing "methods are far more sophisticated than they were before . . . . The technology and the state of the art available to the public is much more advanced: copying machines, printing techniques, the availability of inks, all these things."

The document vendors "really do a good job," he said. And they make good money. Bogus American passports -- either fabricated from scratch or valid passports altered by substituting a page or photo -- can sell for as much as $5,000 or $6,000, Deaner and other experts report. Nonimmigrant U.S. visas run between $600 and $4,000.

In 1982, a group of Filipinos paid $2,000 apiece for what they believed to be valid U.S. visas, according to an investigator with the Immigration and Naturalization Service. But they were detained when they arrived at Los Angeles International Airport. One was so miffed that he readily identified another passenger, one Jose P. Ohide, as the vendor who had sold them the visas. Ohide was convicted of 11 counts of passport fraud in U.S. District Court in Los Angeles in March 1983.

It is hard to get a precise figure for the incidence of passport fraud. Justice Department officials caution that, when a person is convicted of multiple offenses, only the first listed offense makes it into the statistical record book. And passport fraud usually takes a back seat to more significant crimes, they said.

Even so, there has been a steady increase in the number of passport fraud convictions recorded by the department in recent years -- 50 percent over the past three years.

The State Department's Bureau of Consular Affairs and the INS are fighting a two-front war against the problem -- at home and abroad.

Ross Benson of the State Department said that at least one document fraud expert is now assigned to 10 U.S. embassies -- in Colombia, Haiti, Jamaica, Mexico, Korea, Hong Kong, Thailand, the Philippines, the Dominican Republic and Nigeria -- all countries where there is a big demand for U.S. nonimmigrant visas. A decade ago, there was not a single such expert on an embassy staff.

In 1979, the INS also established a Forensic Document Laboratory with a staff of four professional handwriting, ink and paper specialists. They and other experts give regular seminars on the latest methods being used by counterfeiters and document vendors, so that the holders of forged papers can be turned back before they cross the border and gain access to the U.S. court system.

While Benson worries about vendors overseas, Deaner concentrates on the ones at home, whose job, he said, is made easier by the massive, decentralized U.S. system for generating identifying documents. "When you're looking at 7,000 jurisdictions issuing citizenship documentation, you've got a problem," he said.

"The problem is the documents presented to obtain a valid passport," he said. "That's the weak link and where we are trying to concentrate our countermeasures." Thus far, he said, those measures consist largely of seminars and other educational forums for officials who issue birth certificates, drivers' licenses and Social Security cards.

Domestic document vendors, willing to sell these and other "breeder" documents or passports themselves, can be found "on almost any street corner of any large metropolitan area in the country," said Deaner. "If you asked me about New York, San Francisco, Miami, Los Angeles, I'd say, 'Yes,' 'Yes,' 'Yes,' 'Yes.' "

Professional help may not always be needed to get phony documents. One man, wanted for killing a policeman in Florida, was picked up in Spain carrying two different American passports, said a law enforcement source who would not give the fugitive's name.

American investigators believe that the man's girlfriend in southern California used a method depicted in the 1973 film "Day of the Jackal": picking names out of cemeteries of men born the same year as the fugitive. Armed with the names, she obtained birth certificates and used them to obtain passports.

Another problem is lost and stolen passports. About 4.7 million passports were issued last year, and there are more than 20 million valid U.S. passports outstanding, according to State Department figures.

Last year, about 45,000 passports were reported lost or stolen, up from about 40,000 in 1983. That figure, Deaner said, is growing at about the same rate as the number of outstanding passports, which showed a 53 percent increase since 1974.

Officials point out that many of the lost passports are returned to the U.S. government from foreign restaurants, hotels and police authorities and never enter the underground document market.

Still, some do. In Jerusalem last September, according to law enforcement sources, two white American men, in their twenties or thirties, presented their passports to the Israeli Interior Minstry and applied for resident work permits.

Israeli officials queried U.S. government officials, who ran a criminal check on the men's names and found nothing wrong. But a check of the passport numbers revealed that one had originally been issued to a 10-year-old Hawaiian girl and the other to a black man. According to a Justice Department source, the fingerprints of the men in Jerusalem matched fingerprints of men with "long" criminal records.