BOGOTA, COLOMBIA, JULY 17 -- A judicial probe into how hundreds of Israeli assault rifles ordered for the tiny island of Antigua ended up in the hands of Colombian drug lords has turned up new evidence of irregularities that investigators believe should have alerted Israeli officials to problems with the deal.

The Antiguan judicial investigation is focusing on whether any of that nation's officials aided the diversion by providing a false end-user certificate for the Israeli weapons. Investigators say they are also examining the broader question of why Israeli Military Industries (IMI), which makes and sells Israeli government arms, did not check more carefully the unusual nature of the sale last year.

"One would have hoped it would have caused {the government of Israel} to ask questions, unless that is the way business is usually done," said E. Lawrence Barcella Jr., an American investigator hired by Antigua. "And that in itself should raise questions." Barcella, who left the Justice Department four years ago, was an assistant U.S. attorney in the investigation of the 1976 assassination of Chilean ex-ambassador Orlando Letelier in Washington.

The first thing that should have tipped off Israelis that the sale was suspicious, investigators said in recent interviews, was that most of the documents related to the sale were faxed to Israel from Miami, not Antigua -- including the crucial end-user certificate. Such a certificate is required in government-to-government arms sales, certifying the buyer will not pass the weapons on to a third party.

Israeli Military Industries eventually received an original copy of the end-user certificate, the investigators said. But it was only a one-paragraph letter and a description of the goods, rather than a more detailed format, which they said should also have raised questions.

The investigators said the Israelis apparently did not make any serious check of who was buying the weapons. According to the investigators, the arms were consigned to an address in Antigua that does not exist and an addressee, the Quartermaster General of Antigua and Barbuda, that does not exist.

Also, Antigua has just a 90-man defense force, and would not have needed the quantity of equipment allegedly requested -- 400 Galil assault rifles and 100 Uzi machine guns, plus 250,000 rounds of ammunition.

A spokeswoman for the Israeli Embassy in Washington said the government of Israel "did not know {of}, nor did it authorize" the transfer of the Antigua-bound arms to Colombia. The spokeswoman, Ruth Yaron, added: "The arms sold to the government of Antigua were delivered only after the Israeli Military Industry received an end-user certificate from the government of Antigua."

Colombian and U.S. investigators say the arms shipment was part of a deal between Medellin cocaine cartel leader Gonzalo Rodriguez Gacha and Israeli mercenaries to train and arm assassins in Colombia at a time when the drug baron, an extreme rightist who harbored the dream of building a neo-fascist state, was trying to gather strength to overthrow the government.

At the same time the weapons deal was being made, the investigators said, Rodriguez Gacha hired at least three Israeli mercenaries, led by Yair Klein, to train his men in sophisticated military tactics and the use of explosives.

Rodriguez Gacha was killed by police on Dec. 15, 1989, and in a search of one of his rural ranches three weeks later, Colombian police found 178 Galil assault rifles and turned the serial numbers over to Israeli authorities. The Israeli government said the arms had been sold legally to the Antiguan government as part of a shipment of 500 weapons, and that it had no idea the guns would end up in the hands of drug traffickers.

According to Israeli press reports, the Israeli government has argued that the end-user certificate signed by Vere Bird Jr., an Antiguan government minister, makes the sale legal, and that what happened after the arms were delivered to Antigua is not its responsibility.

Bird has said the document is a forgery and that he knows nothing about the sale. Investigators say they believe the key intermediary in the deal was Klein.

Klein has been questioned by the Israeli police regarding allegations of his involvement in the arms sale and has denied them, according to an Israeli source.

Klein is a retired Israeli lieutenant colonel and head of Spearhead Ltd., a Tel Aviv-based security services firm. He is under indictment in Israel on charges of having illegally exported military know-how to Colombia. Klein has admitted training armed groups in Colombia, but said he was told they were cattle ranchers seeking to defend against Marxist guerrillas, and that he had no knowledge they were tied to drug traffickers.

In interviews with Israeli newspapers, Klein has denied any role in supplying the weapons to Rodriguez Gacha, saying the guns were purchased for a training school for Panamanian dissidents who wanted to overthrow Gen. Manuel Noriega. He said the plan was canceled, and that he does not know how the weapons ended up in Colombia.

"Klein claims that the arms and the training were separate operations, but it seems very strange to us that the weapons ended up with the same person {Rodriguez Gacha} who had the training camps," said a U.S. Senate aide who is investigating the arms sale for the Senate permanent subcommittee on investigations.

One account of the weapons deal is contained in a May 1990 Colombian intelligence report obtained by The Washington Post. The report says that in early January 1989, Rodriguez Gacha began to make arrangements for a ship to "go to Israel to pick up a load of arms for Colombia via Panama." At about the same time, his group was negotiating with Klein to provide training to his paramilitary groups. Antiguan and Colombian investigators said they suspect that Klein may initially have sought Panamanian end-user certificates for the arms.

The Colombian intelligence report says Gacha had problems getting a boat to pick up the goods, delaying their shipment. But apparently that was not the only problem. According to the Colombian report, Klein learned sometime in late February from friends in Panama that Noriega planned "to intercept the arms and appropriate them for his own cause."

Klein "opted to change the route of the shipment and made contact with the government of Antigua, where a high official offered to collaborate for $125,000," the Colombian report says.

By March, Klein and two other Israelis, Teddy Milnik and someone known only as "Mike" were training Rodriguez Gacha's men near Puerto Boyaca, Colombia, the Colombian report alleges. An earlier intelligence report says Klein charged $75,000 for the 20-day course.

Milnik, according to the intelligence report, is a retired captain in the Israeli army, who served as Klein's translator. The report says Milnik had a valid Israeli passport as well as a Chilean passport.

By the end of the training course, investigators said, Rodriguez Gacha was furious that the weapons he had paid for had not arrived. To be sure he received his goods, he took Milnik and "Mike" hostage, while Klein scrambled to keep his men from being killed.

The weapons were aboard the Danish ship Else TH, carrying legally purchased Israeli weapons to be dropped at Colombia, Ecuador and Chile, accompanied by an Israeli merchant marine captain named Philip Eron to oversee the deliveries.

"Shipmaster Philip Eron was indeed aboard the cargo ship with the arms for Antigua. He was there as a representative of IMI," said the Israeli spokeswoman. An Israeli source added that Eron has been questioned by Antiguan and Colombian investigators, and that "he confirmed to each one of them that the arms were unloaded in Antigua."

Once the weapons had arrived in Antigua, Klein still had another problem -- how to get them to Colombia, according to investigators.

Investigators say that Rodriguez Gacha offered to provide a ship, the Sea Point, of Panamanian flag, to move the weapons to Colombia, but there was a catch. The Sea Point was in San Juan, Puerto Rico, and loaded with wood. If Klein wanted to use the boat, he would have to buy the load of wood aboard, which investigators say he agreed to do.

According to shipping documents seen by The Post, the Else arrived in Antigua on April 24, as did the Sea Point. A container of arms was unloaded and put aboard the Sea Point, according to investigators. They said the wood was given to an accountant who worked for a local Israeli businessman, to dispose of as seen fit.

The Sea Point left hours later, according to shipping records. The two Israeli hostages were released April 29, according to investigators. The Israelis fled the country shortly afterward when the Colombian government became aware of their activities and ordered their arrest, investigators said.

The Colombian intelligence report says the Sea Point then sailed near the Colombian island of Isla Fuerte, off the northeast coast of Colombia, where it contacted a yacht belonging to Rodriguez Gacha, and where the weapons were unloaded and taken to a farm on the mainland.

In August 1989, the Sea Point was seized off Mexico for transporting cocaine, according to an U.S. government official investigating the shipment.