Fear of electoral violence rose in the Philippines today when explosions disrupted an opposition rally in Zamboanga and a slain campaign worker was buried in the tense Luzon town of Capas.

Presidential nominee Corazon Aquino and her running mate, Salvador Laurel, were on stage when the first blast, a grenade, startled the crowd at Zamboanga on the southern island of Mindanao. Police said the grenade exploded in a park two blocks away. There were no serious injuries.

Shortly afterward, another report was heard. Aquino said that an aide told her it was a car backfiring, but police speculated that it was a firecracker. Officers said that there were no arrests and that they had no suspects.

Meanwhile in Capas, north of Manila, a nervous crowd attended funeral rites for Jeremias de Jesus, an Aquino campaign worker shot to death Wednesday. Supporters of Aquino, wearing yellow T-shirts and dresses, the color of her campaign, filled the church. Mourners watched outsiders closely.

De Jesus' body arrived at the church in a hearse bearing his bloodied shirt on the hood.

Jose Feliciano, the local Aquino campaign manager, said that the killing of de Jesus and his driver had frightened opposition supporters in the town and led several members of a civilian poll-watching group to resign.

"These deaths will make people more bold," he asserted, but he conceded also that they "strike terror" in the opposition camp.

A companion of de Jesus and the driver, Alberto Briones, reportedly identified the gunman as a paramilitary security man assigned to Capas Mayor Rafael Suarez. Suarez, a member of President Ferdinand Marcos' ruling party, told reporters at his home that the security man was innocent and that witnesses had placed him at another location.