MANILA, OCT. 4 (THURSDAY) -- Mutinous Philippine troops seized control of an army command post on Mindanao island, then marched triumphantly into two nearby cities, prompting a nationwide military alert and fears here that the rebellion could be a prelude to troop uprisings around the archipelago or even an all-out coup attempt.

Manila officials said the mutiny began shortly after midnight when about 400 men of the 53rd Infantry Battalion occupied the headquarters of the 402nd Infantry Brigade in Butuan City, about 500 miles south of Manila. They said no shots were fired and that soldiers stationed inside the camp apparently made no effort to resist the rebels.

In a nationwide radio broadcast five hours later, the Philippine armed forces chief, Gen. Renato de Villa, announced that the rebel group was led by two officers he identified only as a "Maj. Cerdeno" and "Lt. Batac," and that the incident was "a small thing" that could be easily controlled.

But intelligence sources said soon afterward that it appeared renegade army Col. Alexander Noble, the former deputy commander of President Corazon Aquino's presidential guard, had been involved in the base seizure, and later accounts from the region indicated that troops led by Noble had also occupied portions of Butuan City itself and of Cagayan de Oro, a city of 225,000 about 70 miles to the west.

{The Reuter news agency reported that a column of troops and military vehicles headed by Noble had entered Cagayan de Oro after earlier taking over key sites in Butuan City, which has about 175,000 residents. Leaflets distributed by the rebels in both cities declared: "This is an announcement that the war for the liberation of Mindanao has started."

{The rebel troops displayed red, blue and green flags representing an independent Mindanao and were met on the outskirts of Cagayan de Oro by Ruben Canoy, head of a political movement seeking Mindanao's secession from the Philippines.

{Noble, who has been the object of an intensive search by government forces since last December when he took part in the most recent previous troop rebellion, entered Cagayan de Oro atop an armored car to the cheers of about 3,000 local residents. The rebels met no resistance, and troops loyal to Aquino barricaded themselves inside the city's Patag military camp behind barbed wire defenses.

{About two hours after the mutineers entered Cagayan de Oro, Reuter reported, government warplanes strafed rebel troops advancing on an army camp near Iligan City, about 35 miles farther west. It was the first reported gunfire of the revolt.}

Officials in Manila said that the rebels had apparently cut communication lines between the affected Mindanao region and military-command headquarters in the capital, and it was unclear late this morning if the rebels intended to make any demands on Aquino's government.

Aquino met with her cabinet, senior military officers and congressmen at the presidential palace, and in a radio address afterwards she appealed for support from the public. "I'm calling once again on the people to rally against these troublemakers," Aquino said. "The constitution will be upheld with force when challenged with force."

De Villa said in his broadcast that he had placed the 160,000-member armed forces on full combat alert and that commercial airline flights to and from Mindanao, the second largest island in the Philippines after Luzon, had been canceled. "We can handle it," de Villa said, apparently before reports reached the capital that the insurrection had spread from the brigade headquarters to the two Mindanao cities. "The armed forces are united except for that group in Butuan," he said. "Our troops are obeying our orders completely."

De Villa also appealed to the mutineers to surrender. "I just want to tell them that this uprising is a big mistake and may endanger our civilians," he said.

Rebellious army units, charging that Aquino is incapable of dealing with communist rebels in the countryside and corruption in her government, have previously launched six attempts to topple her government since she swept to power in a popular revolution in 1986. The most serious occured in December, when heavily armed rebels took over several army bases around Manila and held the capital's financial district for a week in a bloody conflict with loyalist forces that left scores dead and hundreds wounded.

One army intelligence officer said today that if the military fails to contain the latest outbreak, "Mindanao will be a sideshow" -- meaning that rebellious troops might seize the opportunity to stage similar risings at bases and cities throughout the 7,000-island archipelago.

Prior to this morning's revolt, military sources in Manila said they had obtained intelligence reports that officers involved in last December's fighting were planning attacks in Mindanao to be followed by coordinated assaults elsewhere.

Rebel sources as well had boasted to reporters of their "enclave concept," which they said was designed to force the military to spread out its forces, leaving Manila, the seat of power, vulnerable to attack. "We will go for the jugular," declared rebel Maj. Abraham Purugganan of the underground Young Officers Union in an interview last week.

Military officials here said loyal troops were being dispatched to Mindanao, but they could provide few details of how the high command intended to respond to the insurrection.

Noble, once a highly respected commander in the regular army, is thought to be still highly regarded among both rebel and loyalist officers and troops. There is now a $20,000 reward for his capture, and last July government forces staged a exhaustive search operation for him through some of the most rugged terrain in Mindanao, where he went into hiding following the failed December coup.

During that rebellion, Noble traveled from Mindanao to Manila to lead a ground assault on the presidential palace, but he was unable to link up with the troops he was to lead. He returned to Mindanao with the aid of sympathetic army officers, who at one point arrested him and allowed him to escape. He later took refuge in the mountains of Agusan Del Sur province, surrounded by a band of about 300 tribesmen he had trained personally.

Local military commanders in Mindanao had operated in an uneasy truce with Noble's forces until last May, when Noble publicly signed an agreement to support the island's secessionist movement.

{In Washington, hours before the onset of the mutiny, U.S. congressmen and administration officials issued a warning to potential Philippine coup plotters that U.S. aid will be cut off if they overthrow Aquino, and that it would not be resumed so long as they are in power, Reuter reported.

{The unusual warning was issued at a hearing of the House Asian and Pacific Affairs subcommittee. Chairman Stephen Solarz ( D-N.Y.) said he had a message for anyone who believes U.S. aid would only be cut off for a short time because Washington would not jeopardize negotiations on keeping U.S. military bases in the Philippines.

{"You are dead wrong," Solarz said. "I can assure any potential coup plotters that regardless of its impact on the ongoing base negotiations, there will be no resumption of U.S. aid to the perpetrators of a coup, or to any figurehead regime that they try to install in power."}