Communist guerrillas mounted unusually intense and widespread attacks in the south, central and northern Philippines this week to mark the 16th anniversary Friday of the founding of the New People's Army.

Sixty-six people including rebels, soldiers and civilians were killed and 75 others were wounded in clashes over the last three days -- an unusually high casualty rate, according to official military sources and local press reports.

The armed forces acting chief of staff, Lt. Gen. Fidel Ramos, ordered a red alert in anticipation of attacks on the anniversary.

The general's statement said the rebels could be planning to assault government installations and ordered all commanders to give maximum security to armories, provincial and city jails and municipal town halls. He canceled all police and military leaves throughout the Philippines.

Local newspapers quoted military sources as saying the Communists planned to lay siege to parts of Davao City in eastern Mindanao which has become the insurgent's testing ground for urban guerrilla warfare.

Stepped-up attacks by the New People's Army, which was founded in central Luzon on March 29, 1969, were usual at the time of the anniversary in previous years. But this year's clashes have escalated dramatically because of the growing strength of the guerrilla army, officially put at 12,000 men.

The most dramatic incident yet was the bold raid by 20 rebels on the Visayan Maritime Academy in the heart of Bacolod City in the central Philippines Monday night. The guerrillas carted away more 400 firearms in the biggest haul yet by the NPA of government firearms.

The armed forces, however, said only 140 guns taken were in operational condition. Police conducted a sweep of residential areas looking for arms caches in the belief that the guns had not left the city. Checkpoints were set up in many areas.

The police said they might search the quarters of Roman Catholic priests and nuns known to have antimilitary sentiments. Church-state relations in economically depressed Negros Island have been strained for years.

Defense Minister Juan Ponce Enrile in an interview on Tuesday admitted that the situation is worrisome in Negros Island, where the end of sugar production there has deprived 400,000 sugar workers and their dependents of a source of income.

The highest death toll this week occurred yesterday in Misamis Oriental Province, North Mindanao, where 150 guerrillas killed 20 villagers and wounded 50 others following the murder of two rebel fighters by a religious cult.

A mayor in Zamboanga del Sur Province in southwest Mindanao and his daughter were killed when his jeep was attacked by guerrillas. In Agusan del Sur Province in northeast Mindanao, six village officials were killed. Incidents were also reported in Iloilo in the central Philippines and the tribal area of Kalinga-Apayao in the north.