Benigno S. Aquino Jr., the slain opposition leader, was given his final honors as a political martyr today and buried after a funeral procession that drew hundreds of thousands of admirers into the streets.

Ten days after he was slain at Manila's airport, Aquino's body, in a flag-draped casket, was driven on a 19-mile, 11-hour journey that ended with a simple ceremony at a cemetery vault.

The long march was free of trouble. Adoring crowds cheered when his coffin approached and sang patriotic songs. Again and again the streets thundered with shouts of his nickname--"Ninoy, Ninoy, Ninoy."

There were, too, signs of political protest against his long-time enemy, President Ferdinand E. Marcos, but it was for the most part a cheerful throng from which the hard edge of political hatred was missing.

The dominant mood was one of affection, not grief or anger, and it was perhaps best summed up by the hundreds of signs and T-shirts bearing Aquino's picture and a simple phrase in Tagalog, the main indigenous language: "Ninoy, you are not alone."

Late tonight, between 1,000 and 2,000 college students and neighborhood youths threw rocks and bottles and burned tires a few blocks from the presidential palace. One student was reported killed and 18 persons injured in clashes with police. Some homemade explosives were thrown and police responded with fire hoses and clubs. The sharp cracks of what sounded like gunfire could be heard at one point. Police blocked off all streets leading to Malacanang Palace, Marcos' residence.

The Associated Press reported that during the funeral procession and the buildup of student violence in the darkened streets of the university district, the president's wife, Imelda Marcos, gave a dinner at the palace for U.S. Sen. Mark Hatfield (R-Ore.) who, a U.S. Embassy spokesman said, was on a private visit. Rick Rolf, Hatfield's press secretary, said in Washington that the senator was in the Philippines to visit places where he had fought in World War II and to give a speech at the University of the Philippines.

The funeral procession wound from Aquino's neighborhood church, Santo Domingo, through downtown Manila, passing some distance from Malacanang Palace.

As the procession crossed Rizal Park near Manila Bay, some in the huge crowd hauled the Philippine flag down to half staff in salute to the politican who had wanted to become president but who had spent the last decade of his life either in prison or in self-imposed exile in the United States.

It was there that the crowd's only gesture of hostility erupted. A swooping helicopter suspected of carrying a military crew was lustily jeered. Actually, the helicopter carried a television team photographing the scene below.

Crowds, sometimes a dozen persons deep, lined the entire route and behind the procession followed a long line of cars, vans and the elaborately decorated "jeepneys" that Filipinos use as mass transit. People climbed to the tops of buildings and hung from trees and towers to watch.

A downpour accompanied by lightning and thunder drenched the crowd at one point. A man was killed when lightning struck the tree he had climbed for a better view.

Aquino was shot to death Aug. 21 as he emerged under guard from an airliner. The government asserts that he was slain by a lone gunman who has a record as a hired killer.

But with many questions unanswered and a high-level investigation yet to begin, the government version has aroused widespread skepticsm. Many suspect some form of government complicity and believe the truth will never surface.

Marcos' 18-year-old government has a record of jailing and harassing political opponents and its reputation for stifling dissent was attacked in the funeral homily delivered today by Cardinal Jaime Sin, archbishop of Manila.

Peering over Aquino's coffin at a packed church audience, the cardinal referred to an "atmosphere of oppression and corruption, the climate of fear and anguish" and said that the Filipino "has become an exile in his own country."

"In his own land," said the archbishop, the Filipino "must only whisper--and never shout--what is true. He must tremble before those who were sworn to serve him and he must hide his children if they refuse to bow down to tyranny."

Aquino, he added, had "personified the Filipino's courage in the face of oppression."

In the casket, the top part of Aquino's body was visible through a sheet of glass and his face was scarred where the fatal bullet had emerged. He had been shot from the rear behind his left ear.

Lines had formed outside the church three hours before the funeral mass began at 8:25 a.m. U.S. Ambassador Michael Armacost attended, along with several diplomats from Europe and Japan, but there were no official delegations from the Philippines' Southeast Asian neighbors.

The government, which had no comment on the funeral tonight, made no effort to hinder the procession. A government-controlled television station tonight made only cursory mention of the funeral on its evening news program.