The FA-50 fighter jet had gone missing a day earlier while on a mission to provide air support for troops fighting guerrillas in northern Mindanao.

Lieutenant General Luis Rex Bergante, commander of Eastern Mindanao Command, told AFP the two crewmen had been found inside the wreckage.

"The bodies were found inside the aircraft. There was an attempt to open a parachute and eject," he said.

"The aircraft was a total wreck. The aircraft smashed through the trees in the mountain."

Lieutenant Colonel Francisco Garello of the 4th Infantry Division told AFP the wreckage of the missing jet was found on Mount Kalatungan.

Located in Mindanao's Bukidnon province, the 2,880-metre (9,450 feet) Kalatungan is the fifth-tallest mountain in the Philippines.

Bergante said bringing the servicemen's remains down the mountainside was now the top priority.

In a statement, the air force said it had temporarily "grounded its FA-50 fleet" and would "ensure a thorough investigation into the accident", the cause of which remains unknown.

The crashed jet was one of a dozen FA-50s the Philippines purchased from South Korea in the past decade.

- Dangerous terrain -

Garello said early Wednesday that the search had been suspended overnight due to the danger of "communist groups" believed to be operating in the area.

On Tuesday, he said his division had called in air support during a firefight with the New People's Army, a long-running Maoist insurgency now believed to have fewer than 2,000 fighters.

The jets flew out of Mactan-Benito Ebuen Air Base, which shares a runway with the airport in Cebu, the Philippines' second-largest city.

Air force spokeswoman Colonel Consuelo Castillo told reporters Tuesday it was the "first major incident" involving its squadron of FA-50s, which have been used in exercises over the disputed South China Sea.

The FA-50s have been flown in joint air patrols with treaty ally the United States over contested areas of the South China Sea, where China and the Philippines have been involved in increasingly tense confrontations.

On Wednesday, Castillo said the air force hoped the investigation would be "done thoroughly but swift enough for us not to sacrifice our operational readiness" given the fighters' key role in maritime patrols.

She also said the air force has proposed purchasing 12 more FA-50s, a request under consideration at the Department of National Defense.

There have been a number of deadly crashes involving Philippine military aircraft in recent years.

Two navy pilots were killed last April when their Robinson R22 helicopter crashed near a market south of the capital Manila during a training flight.

Two PAF pilots were killed in January 2023 when their Marchetti SF260 turboprop plane crashed into a rice field.