A Philippine police officer was confined to barracks today after witnesses reported that he had led a gang of gunmen who murdered a senior figure in the campaign of opposition presidential candidate Corazon Aquino yesterday, the official Philippine News Agency reported today.

The detention came as Aquino's campaign released an interview that the victim, Harvard-educated Evelio Javier, taped shortly before his death. In it, he said he had been repeatedly harassed by armed men sent by Arturo Pacificador, the major political power in the central province of Antique and a close associate of President Ferdinand Marcos.

"Every time I move around Antique, I have to play cat and mouse with Pacificador's guards," Javier said on tape. "In any case, we expect the worst . . . we don't have arms. We are really just sitting ducks."

"Should anything happen to me, there is nobody else who has the motive to have me liquidated, except Mr. Pacificador," Javier said.

This morning, about 150 people attended a mass for Javier held in Aquino's campaign headquarters here. The murder, coming together with the sniper killing of a young supporter of Aquino in Manila's financial district, is shaping up as a major political arguing point.

Javier's body is to arrive by air in Manila on Thursday. Aquino is expected to join a motorcade that will take the body to a church.

Pacificador, who is assistant majority floor leader in the National Assembly for Marcos' party, denied any involvement.

Javier was chased by as many as six men in the town of San Jose, 275 miles south of Manila. After wounding him on the street, they cornered him in a toilet where he tried to take refuge. They fired M16 rifles through the closed door. Opening it, they fired a final shot into his head to make sure he was dead, it was reported.

Pacificador defeated Javier, a former governor of Antique, in a 1984 election. During that race, six of Javier's campaign workers were killed in a mass slaying.

Today, Pacificador suggested that the murder of Javier had been carried out by the opposition. "Or is this a ploy of the Communist Party, of which the UNIDO is a part?" he asked. UNIDO is the opposition party backing Aquino.

Witnesses said the killers had arrived in two jeeps that had been used in campaign activities of Marcos' party. Pacificador said he had a jeep matching the description but asked why he would allow it to be used if he had ordered the killing.

Pacificador suggested that opposition Antique Gov. Enrique Zaldivar might be behind the murder.

The implicated police officer was identified as Capt. John Paloy.