MANAGUA, NICARAGUA, JULY 22 -- Government troops for the first time have captured a CIA-supplied Redeye antiaircraft missile from Nicaraguan rebels, Defense Minister Gen. Humberto Ortega announced today.

The action marked the fifth CIA-run air drop intercepted this year, Ortega said.

Since January, when the rebels went on a prolonged offensive after receiving a new infusion of U.S. aid, both sides have said that the air war is central to the fighting. Guerrilla leaders said the CIA-managed air resupply flights are crucial to sustaining their operations deep inside Nicaragua.

The rebels, known as contras, succeeded in hampering some Sandinista helicopter assaults with the heat-seeking Redeyes, acquired since February as part of the $100 million U.S. aid package, U.S. military officers said.

The missile, numbered M41A3, was captured July 19 in Chontales province, about 125 miles southeast of the capital, Ortega said. He said an airplane flying north from Costa Rica dropped a small paratroop team and their weapons, including the missile in a metal container lashed between car tires to cushion its fall.

The rebel paratroopers escaped, according to Ortega, but a specialized Sandinista interception unit blocked them from retrieving their weapons. The Sandinistas also captured four parachutes and three helmets at the site, not far from where an air resupply flight carrying flier Eugene Hasenfus was shot down in October 1986.

Ortega displayed the U.S. Army Redeye, with the missile still ready to fire inside the launcher-barrel, at a press conference, along with parachutes and helmets.

Ortega charged that since 1985, the United States has given the contras about 200 antiaircraft weapons, including Redeyes and Soviet-made SA7 missiles. He also predicted that the contras, in desperation, would sell some of the missiles on the Central American black market in exchange for other weapons.

Ortega suggested that it would not be unusual for leftist guerrillas fighting the U.S.-supported Christian Democratic government in El Salvador to buy some missiles. That statement might have been meant to pave the way for the Salvadoran rebels, allies of the Sandinistas, to obtain and use antiaircraft missiles against the more than 70 U.S.-supplied military helicopters in that country.

In the past, Ortega warned that if Washington provided Redeyes to the contras, the Sandinistas would feel justified in giving antiaircraft weapons to the Salvadoran rebels. "We are not going to dig into our arsenals and tell the Salvadorans, now we have these for you," Ortega said. But he added, "At any rate, if we do that we're not going to talk about it."

Ortega stressed his view that contra leaders, particularly those operating in southern Nicaragua, have suffered sharp setbacks and no longer control what their rebels do with weapons given them by the United States.

He also warned that the contras "We don't put these things in a museum."

-- Defense Minister Humberto Ortega

could commit acts of terrorism with the missiles and accused the United States of endangering commercial aviation in the region.

According to Ortega, special Sandinista air resupply intercept units captured one drop on Feb. 20 in Central Zelaya province, recovering 7,000 pounds of ammunition and supplies.

In early May, he said, in southern Rio San Juan province, Sandinista troops ambushed eight contra paratroopers during a jump, killing two. Ortega said that two other members of that contra team were presented May 12 at a press conference in Costa Rica by Security Minister Hernan Garron and are being held by Costa Rican immigration authorities.

On June 7, in the southern Nueva Guinea region, Sandinista soldiers seized a contra drop with 70 rifles, Ortega said. On July 6, he charged, a contra plane was damaged by Sandinista ground fire and crashed inside Costa Rica.

Ortega charged that many of the CIA-run flights continue to leave from military airfields in El Salvador and use the same routes followed by the Hasenfus flight, whose downing gave rise to the Iran-contra affair.

He accused Salvadoran President Jose Napoleon Duarte of openly becoming "the principal support" for contra resupply operations.

Ortega acknowledged that the Sandinista army has Soviet-supplied C3M antiaircraft weapons, which he said are equivalent to the Redeye.

He said Sandinista troops plan to use the captured Redeye against secret contra flights. "We don't put these things in a museum," he said.