MALUANA, MOZAMBIQUE, NOV. 29 -- Rightist guerrillas killed at least 63 persons and wounded 78 in their third attack in two months on an Army-escorted civilian convoy north of Maputo, hospital and government officials said today.

The officials accused the Mozambique National Resistance, or Renamo, of carrying out the attack yesterday near Maluana, 32 miles from Maputo, the capital.

Thirty-two charred and burning trucks and buses lined the road for almost a mile. The burned bodies of some of the drivers were found still behind steering wheels.

The wrecks included two giant trucks jackknifed across the road. One truck bore stained markings of the U.S. Agency for International Development. The cargo of food destined for the drought-stricken northern provinces had been partly looted and then burned.

A political commissar of the Marxist government of Mozambique said "three trucks were used to carry the dead and wounded to Manhica," a town about 12 miles to the north.

The Portuguese news agency Lusa said in a report monitored in Lisbon that soldiers guarding the convoy and warplanes called in to assist attacked the rebels, killing at least four of them.

The agency said the rebels let military escort vehicles and a few civilian trucks pass before opening fire on the convoy.

A survivor, Salvador Manuel, said rebels attacked the convoy along its length. "They fired from both sides of the road," he said.

Manuel, a passenger in one of three attacked buses, said he escaped by smashing a window and crawling away through the bush.

"The bandits demanded that people give them things if they wanted to stay alive," he said. "I saw one man demand a watch from a woman. She said she did not have one and he told her to go in front. He was distracted for a moment and she ran away under some cashew trees."

The Mozambique News Agency, AIM, said rebels killed 330 people in two similar ambushes on Oct. 16 and Oct. 29 about 50 miles north of Maputo. Mozambican officials accused neighboring South Africa of responsibility for the earlier attacks, saying Pretoria supported the rebels in a policy designed to destabilize the country.

South Africa rejected the accusation and Renamo accused Army deserters or counterinsurgency units seeking to embarrass the rebels of committing the attacks.

Troops defending the convoy killed at least four rebels before the attackers -- who normally operate in the zone in units of up to 300 men armed with bazookas and machine guns -- withdrew at "the approach of Air Force planes," Lusa said, quoting a military source.

In the past six months, the rebels, who operate across the former Portuguese colony of 13 million people, have increased attacks in the far south around Maputo. Diplomats said the offensive appeared aimed at cutting off the Indian Ocean capital from the rest of the country. They said there now was practically no road or rail traffic out of or into Maputo without military escort.