BOGOTA, COLOMBIA, JUNE 11 -- Colombian officials are claiming that the United States and Israel have failed to stem the flow of weapons to this country's drug traffickers, who are using them to kill hundreds of policemen and others. U.S. officials acknowledge that perhaps 80 percent of the arms are American.

The Colombians say a growing influx of sophisticated arms, along with past training by Israeli and British mercenaries in attack methods and the use of explosives, have made the Medellin cocaine cartel an efficient army, able to protect its illegal trade and to wage war against the government.

"We are asking countries to exercise much greater control over the free sale of arms, because it does us great damage," said Gen. Miguel Gomez Padilla, director of the National Police, in a recent press conference. "With less easy access to arms, narco-terrorism would cause us less damage." About 390 policemen have been killed this year, more than half in Medellin.

"It is true that a substantial amount of the weapons, possibly as much as 80 percent, are of U.S. origin," said a U.S. official here who monitors the situation. "Our best estimate is that they are brought by returning aircraft after dropping cocaine."

The weapons, sold legally in the United States as semiautomatics, can be modified into automatic weapons in a matter of hours, the authorities said. The officials say the weapons -- Ingram and MAC-13 machine pistols used in killing three presidential candidates, M-16s, AR-15, and AK-47 assault rifles -- are bought two or three at a time and shipped to Colombia in lots of 15 or 20 on small airplanes returning after dropping cocaine.

An ex-official who is now a close adviser to President-elect Cesar Gaviria said bitterly, "The United States has decided to declare war on drugs until not one Colombian is left standing."

"The United States does not really care for our interests," said another senior official normally friendly to the United States. "Recent developments show there is no real interest in helping us, through control on arms or anything else. The United States is not willing to make any sacrifices."

But the Colombian's greatest wrath is directed at Israel, because of a largely successful scheme laid to Israeli mercenaries to train assassins in the pay of the Medellin cocaine cartel and sell arms to the drug barons. Many charge that, despite denials, Israel's government knew of it, or should have.

"The Israeli government would have to be very foolish or very naive not to have known what was going on," said a senior official. "And the Israelis are neither. But the truth is, as this shows, they will sell anything to anyone if the price is right."

In December, police found 178 Galil assault rifles -- from an official Israeli shipment of weapons to the government of Antigua -- on the farm of slain drug runner Gonzalo Rodriguez Gacha.

The rifles were part of a lot of 400 Galils, 100 Uzis and 200,000 rounds of ammunition, allegedly bought by Antigua for its 80-man defense force. Colombian and diplomatic sources say the arms, after arriving in Antigua on April 23, 1989, were transported to Colombia, into the hands of Rodriguez Gacha.

The Israeli Embassy here says the arms were sold to the government of Antigua under the usual procedures for selling arms to another government, and says its government had nothing to do with the weapons ending up in the hands of Rodriguez Gacha. Colombian officials point out that the sale of 500 such weapons for a force with 80 men should itself have raised questions in Tel Aviv.

Colombian investigators say they are now investigating possible military and government involvement in what may have been a second, much larger shipment of weapons from Israel to the drug traffickers arriving about the same time as the Antigua shipment.

A source close to the investigation said, "It is not just an internal problem, but an international scandal. The situation is very grave."

In May, Colombia suspended a 1962 treaty with Israel and imposed visa restrictions on Israeli citizens.

Investigators complain that Israel has provided no real help in tracing arms shipments, despite proof that some Israeli weapons ended up in the hands of traffickers' gunmen.

Colombian intelligence reports say the leader of the mercenaries, as well as of the arms sales, was Yair Klein, a retired Israeli lieutenant colonel and private security specialist who had close ties to the Israeli Embassy here. According to Colombian police, Klein and several other retired Israeli officers, along with 11 Britons and two Australians, were in the pay of Rodriguez Gacha.

In interviews with the Colombian press last October, Klein, who was indicted in Israel last month on charges of illegally exporting military equipment to Colombia, said he was training cattle ranchers to defend themselves against Marxist guerrillas, and that he had no knowledge of those who hired him being involved with drug traffickers.

But Gen. Miguel Maza Marquez, director of the Department of Adminstrative Security, the equivalent of the FBI, said Klein knew who he was dealing with, and was responsible for training the plotters who blew up a commercial airliner last November, killing 117 people, as well as other attacks that have rocked Colombia in recent months.

"He is the person who has done the most damage to Colombia," Maza said in a February press conference. "He is the person who trained these people in the making of bombs and is responsible for this aggression."