MANILA, Philippines (AP) _ The chief of the government's human rights watchdog agency said Thursday allegations of widespread abuse raised by Amnesty International were exaggerated.

Mary Concepcion Bautista, chairman of the government's Human Rights Commission, made the statement after two human rights groups criticized the government of President Corazon Aquino on Wednesday for allegedly using torture and terror to stem a 19-year-old insurgency by communist rebels.

Meanwhile, a former defense minister said the guerrillas were making major gains while the military has become increasingly plagued by infighting and lack of equipment.

The activist Task Force-Detainees, a private group supported by the Roman Catholic Church, said that its investigation showed that 7,444 Filipino civilians were arrested illegally in 1987, eclipsing the 5,967 arrests in 1985, when Ferdinand Marcos was president.

Spokesman Noel Salazar said his group's investigations showed that 602 of those people arrested illegally were tortured.

Aquino rose to power when Marcos' authoritarian regime collapsed in Feburary 1986.

The Task Force-Detainees allegations followed a critical report released Wednesday in London by Amnesty International.

The human rights organization called on Aquino's government to end killings by military and paramilitary forces, saying they represented the country's most serious human rights problem since mid-1987.

''It is exaggerated,'' Mrs. Bautista said of the Amnesty report. ''It's a very one-sided story.''

She said the government was investigating about 200 cases of human rights abuses and that civil suits were pending in the courts against offenders.

''We have ongoing investigations,'' she added. ''They're not all saints in the military ... but there is a serious effort to clean up.''

Mrs. Bautista said investigations of human rights abuses against the military were often not publicized to avoid demoralizing soldiers fighting the rebels.

Amnesty praised the Aquino government for ''some very real progress'' in human rights, particularly in restoring legal safeguards and in greatly reducing the use of torture. But it called on the government to reaffirm publicly its commitment to protect human rights.

In Manila, Sen. Juan Ponce Enrile told the American Chamber of Commerce that divisions in the 160,000-strong armed forces and a lack of supplies were hindering the effort against the communist rebels.

''The situation has become much more delicate than it was before, not only because of the qualitative improvement of the capabilities of the insurgents but also because of the fragmentation in the military organization and the lack of logistics needed to deal with this problem,'' he said.

Enrile, a former defense minister, said the communist army has between 25,000 and 30,000 fighters and controls more territory than at any time during the rebellion.

Police captured reputed guerrilla leader Nemesio Demafiles at a private home in Bacolod, about 300 miles south of Manila, Brig. Gen. Domingo Rio said.

Rio said police seized three other rebels in the Wednesday raid and found a .45-caliber pistol and a map of a nearby Philippine Constabulary headquarters. Rio alleged that Demafiles apparently was planning to attack the constabulary.

Demafiles was believed to be a member of the outlawed Communist Party of the Philippines' central committee and commander of the party's military wing on Negros Island, said Col. Oscar Florendo, chief military spokesman.

The military had offered a $5,000 reward for his capture.

Rebel sources in Manila said Demafiles was removed last year as Negros commander and expelled from the party over an ideological dispute. They said he had been trying to organize a separate Marxist group.

Elsewhere, the military said troops killed the head of a rebel propaganda unit and captured four other guerrillas Tuesday in Luzon's Nueva Ecija province.