MANILA, SEPT. 4 -- Police today raided an office building owned by Sen. Juan Ponce Enrile and seized several M16 automatic rifles, several Israeli-made Galil rifles, a box of grenades, a grenade launcher, a bazooka, land mines and detonators, and thousands of rounds of ammunition packed in crates.

Brig. Gen. Alexander Aguirre, the officer in charge of security for the Manila region, said the arsenal contained enough explosives to destroy a city block. Police officials and political leaders here said the markings on the crates indicated that the weapons and ammunition were the property of the Philippine armed forces.

The raid on the office appeared to mark an escalation of the Aquino government's pressure on Enrile, an outspoken critic whom many presidential aides consider the greatest threat to the government's security. President Corazon Aquino fired Enrile last November amid reports that officers had planned a coup then to install Enrile in power. Some of the same officers were involved in last Friday's revolt.

Police staged the raid as officials here intensified their search for Col. Gregorio (Gringo) Honasan, leader of last week's violent coup attempt that claimed 53 lives, and arrested his brother, Don, charging him with illegal possession of firearms.

Gregorio Honasan escaped when the coup collapsed. Military authorities have suggested in recent days that the renegade colonel may be hiding in Manila, with one military spokesman saying Honasan may be hiding in Makati, the business center and posh residential section of the city.

{In a 15-minute taped message broadcast in Manila, Honasan said that he regretted the casualties caused during the coup and that he never intended to harm Aquino, The Associated Press reported. Aquino said this week that one of the rebels' objectives was to kill her.

{Honasan vowed to continue his fight against the Aquino government, saying it was well on its way to duplicating the excesses of deposed president Ferdinand Marcos. "This we cannot allow and we shall not allow," he said on the tape.}

The office building in which the weapons were found today is in Makati, and Enrile -- Honasan's former boss and mentor at the Defense Ministry -- lives in Makati.

Manila governor Jejomar Binay said the building was owned by a holding company called Jaka. Binay said Jaka stood for Jackie and Katrina, the names of Enrile's two children.

In a report prepared after he took his seat in the Senate, Enrile listed Jaka Investments and Realty as his holding company, controlling several of his business interests. On that report, Enrile listed his net worth as 35 million pesos, or about $1.7 million.

One of the tenants in the office building is Sigma Security Systems, which is widely believed to be owned by Jaka. Binay said an official of the security firm was present during the raid, but refused to claim ownership of the arsenal.

Neither Enrile nor his spokesman could be contacted for comment late tonight.

Even before last week's coup attempt, Enrile had come under pressure from a presidential commission looking into his past business dealings under Marcos. The commission has filed several lawsuits accusing Enrile and other associates of Marcos of amassing wealth illegally.

Enrile has denied any involvement in last Friday's coup attempt. But he remained in seclusion through most of the fighting, turning down a request by a U.S. Embassy official that he intervene to stop the bloodshed and disavow the plotters. Three days after the mutiny, Enrile blamed Aquino's "basic failure in national leadership" for prompting "young and idealistic officers" to try to overthrow her.

One source close to Enrile's inner circle said the raid is "a direct hit against him {Enrile}." This source said Enrile's aides fear that the government's next step may be to arrest him.

The source said that by arresting Enrile, who is believed to be the philosophical leader of the rebellious officers, the government could hope to "flush out Honasan and his men."

The arrest of Don Honasan appeared to be a step in that direction. Officials said Honasan was found with an M16 rifle, nine target pistols and several rounds of ammunition in his home.