The Philippine Army is searching for several hundred U.S.- and Israeli-made automatic weapons believed to be in the possession of a private army loyal to a wealthy ally of former president Ferdinand Marcos, a senior Philippine Army officer said today.

Col. Lorenzo Mateo, commander of the Philippines' 3rd Military Region, which encompasses central Luzon, said that his troops already had seized 854 "brand new" M16 automatic rifles and 20,000 rounds of ammunition belonging to the private army of Eduardo Cojuangco, who is considered one of the wealthiest men in the Philippines.

Cojuangco, who has controlled much of the Philippines' coconut industry as well as the San Miguel Corp., the largest conglomerate in the Philippines, fled on Feb. 25 to Hawaii with Marcos, members of Marcos' family and other associates.

Mateo said that as a military officer in central Luzon for more than two decades, he knew many of Cojuangco's aides and security men. He said that he had seen Cojuangco's bodyguards carrying Israeli-made Uzi submachine guns and Galil assault rifles.

Mateo said in an interview with three reporters that he was once told by Cojuangco's security men that Israelis were brought to Palawan Island, the westernmost island in the Philippines, to help train members of Cojuangco's private army. Cojuangco owns a sizable coconut plantation on Palawan Island, just north of Borneo.

Israel's ambassador to the Philippines, Uri M. Gordon, said in answer to questions about Israeli weapons here, "If they are here, I don't know how they got here." Gordon said of the alleged training of Cojuangco's men by Israelis: "This story reached me before, and I checked it out, and nobody in the Israeli government or in the service of the Israeli government carried out such training."

Under Marcos, the Philippine Army tolerated and sometimes supported private armies belonging to Marcos' allies. According to U.S. and Philippine analysts, many of these private armies sprang up because of low morale and inadequate supplies. Disgruntled troops often joined the forces of local strongmen, who held political sway in various regions of the country, particularly in outlying provinces. Under new leadership, the Army is now disarming many private groups.

When Defense Minister Juan Ponce Enrile and Lt. Gen. Fidel Ramos, then vice chief of the armed forces, announced their rebellion against Marcos last month, one reason for the break with Marcos given by Ramos was the general's objections to private armies and the role that the regular Army had played in supplying them with funds and equipment. The new president, Corazon Aquino, appointed Ramos to be the new chief of the armed forces and kept Enrile on as defense minister.

"Ramos is really serious about doing some housecleaning," Mateo said in a two-hour interview at his headquarters at Camp Olivas, 45 miles north of Manila. Mateo was appointed just 11 days ago to replace Brig. Gen. Isidoro de Guzman as regional commander. De Guzman was said to be close to the former armed forces chief, Gen. Fabian Ver, and to Cojuangco.

According to Mateo, de Guzman turned against Marcos "during the last few hours, but it was too late for him." Reformist military officers rejected de Guzman's last-minute offer to switch sides and, according to Lorenzo, he is being retired.

The colonel said he intended to turn over weapons from Cojuangco's private army to the regional police force, which is short of automatic weapons and often suffers the most from attacks by the Communist-led New People's Army. Many of the police carry only pistols.

During the last election campaign, which began in December, opposition leaders attributed killings, intimidation of voters and other electoral irregularities in Cojuangco's home province of Tarlac to armed men loyal to Cojuangco.

"They say that to win an election here, you have to have guns, guts, goons and gold," Mateo said. "And as soon as politicians come to power here, the first thing they do is try to get more firearms."

Mateo said, however, that once Cojuangco fled the country, his troops offered little resistance to Army raiding teams. He said that he was able to negotiate the surrender of many weapons because he knew many of Cojuangco's men personally.

At Hacienda Lucita, the huge sugar plantation owned by the family of President Aquino in Tarlac Province, recent visitors detected a sense of relief that the Cojuangco army is being disarmed. One resident at the plantation said that Cojuangco's men had intimidated people there. He said, however, that some of these same men recently have "come begging" in an attempt to switch sides.

Aquino is a first cousin of Cojuangco, but they belong to opposite sides in a family feud. Since the mid-1960s, the two sides of the family have been engaged in a struggle for power and influence.

Mateo said that Cojuangco was "considered the godfather in this area." He said that given the nature of Philippine politics, "Eduardo had some reason to need guns."

The colonel said that the size of Cojuangco's private army could come to as many as 6,000 men if one counted the security forces on all of the plantations that Cojuangco owned throughout the Philippines.

[In another development, Armed Forces spokesman Col. Luis San Andres denied reports that more than a dozen generals loyal to Marcos were under house arrest, United Press International reported. He said three generals had been "restricted to their quarters" until they report on their activities during the revolt that toppled Marcos.]