The Philippine military tonight said it has identified the assassin of political leader Benigno Aquino Jr. as a man said to be a "notorious killer" who may have been used in the past by organized crime or subversive groups.

Today's announcement came as Cardinal Jaime Sin, archbishop of Manila and leader of the 42 million Roman Catholics in this largely Catholic country, appealed on the eve of Aquino's funeral for national reconciliation and warned that "ugly undercurrents threaten us all" in the aftermath of the assassination.

The government announcement came nine days after Aquino, a key opposition leader, was shot to death at Manila's airport. It provided no clues as to who the killer might have represented or why he committed the assassination.

A brief and somewhat vague announcement said the killer was Rolando Galman y Dawang who lived in the small town of San Miguel in nearby Bulacan Province.

It said paraffin tests on Dawang's hands showed he had fired the .357 magnum pistol that police say was used to kill Aquino when he stepped off an airplane under guard as he returned from three years of self-imposed exile in the United States.

The man now identified as Galman in the government's account was immediately shot to death by security guards and his identity had remained a mystery until today.

The government's account had been met with widespread skepticism here with many Filipinos convinced of some form of government complicity in the death of the man who was considered the strongest rival of President Ferdinand Marcos. Marcos has denied any government involvement. But many people here believe that the assassination was committed on orders of someone in the military or that sloppy security permitted it to happen when Aquino arrived here from the United States and was taken into custody by security agents.

Gen. Prospero Olivas, the chief of police in Manilla who is heading the investigation, said authorities had reached a "definite conclusion" that the man was Galwan, but he gave no details on his background or possible motives in the slaying.

"The assailant is a notorious killer, a gun for hire, and has reportedly been used by various elements, including organized crime, or by subversive elements, possibly for individual vengeance or possibly for armed robbery, car-naping, hijacking, bank holdups or kidnaping for ransom," Olivas said.

Meanwhile, the leader of Philippine Catholics appealed for reconciliation and warned that pent-up anger over the slaying may erupt in trouble.

In a special message at a news conference, Sin said the assassination had left people "angry and restless and there are ugly undercurrents that threaten us all."

The statement voiced the fears of many Filipinos that the elaborate funeral services planned for Aquino Wednesday may result in violence.

The archbishop, an influential figure who often is critical of the government, also blamed the Marcos government for impeding reconciliation by his insensitivity to citizen pleas.

Aquino's body has been viewed by hundreds of thousands of admirers, here and in his native province of Tarlac, and the services planned for Wednesday are arranged to attract another huge outpouring.

After a mass in Santo Domingo Church near the late politician's home, the body in a casket atop a large truck will be driven slowly along a long parade route that winds through downtown Manila and then to a cemetery.

Thousands of people waited silently in the early hours of Wednesday morning outside the church, hoping to get into the service, United Press International reported. About 3,000 got in when the doors opened and many more waited outside.

Police units backed by armored cars were on the streets hours before the funeral, anticipating trouble from emotional crowds lining the motorcade route.

While the government-controlled media, the church, and Aquino's family all have urged calm, rumors of potential violence have swept through Manila for two days. Some have asserted the government would seize on an outbreak of disturbances as a rationale for reimposing martial law, while others have speculated the country's small communist guerrilla movement might attempt to foment chaos in hopes of discrediting both the government and the moderate opposition.

Aquino's brother, Agapito, disclosed today that a large number of "parade marshals" supplied by a militant labor organization known as "May First" will be on hand Wednesday to guard the funeral procession. He said as many as 50,000 men may line the processional route.

Agapito Aquino also said "whispers" are circulating that groups of government agents may be present, intent on disrupting the funeral procession.

Students who admired Aquino also are organizing a "noise campaign" to express sympathy for the slain man. They are asking citizens to blow automobile horns and beat on dishpans in a cacaphony scheduled to begin in the early evening after the burial service.

Only a few small demonstrations have been reported in the eight days since the slaying and except in comments to the foreign press, the opposition to Marcos has refrained from making a political issue out of his death.

But thousands of leaflets were being handed out in the city streets today attacking the government and the pamphlets of at least two dissenting groups called on the Marcos government to resign immediately.

Cardinal Sin, a political force in his own right here, today stressed the need for peace and reconciliation but he also blamed the Marcos government for making those goals difficult to attain.

"The avenues of communication, which could hasten the process of reconciliation, are not as open as they should be," his message stated. "Government is too centralized, too restrictive, and so unreceptive to complaints."

He said that the assassination had "given rise to a volatile situation. The many polarizations that have long smoldered under the surface--church against state, the civilian population against the military, labor against capital, to mention only a few areas--are threatening to come to the fore.

"To defuse them, every effort at reconciliation, at ironing out differences, must be exerted."