MANILA — President Rodrigo Duterte on Monday paid tribute and promised aid to the families of at least 47 soldiers who were killed in an Air Force plane crash over the weekend.

The Hercules C-130 transport plane on Sunday was carrying 96 people, most of them recent Army graduates, when it overshot the runway while trying to land on Jolo island in Sulu province, a haven for militants.

"I commiserate with you, I am as sorrowful as you. And as Commander-in-Chief, ako 'yong pinakanasasaktan (I am the one most hurt)," Duterte said in a speech before military officers at the Western Mindanao Command in Zamboanga City.

The President said he was "very grateful" to the slain soldiers, who "died for our country".

"Gusto ko lang malaman n'yo (I want you to know), we will extend all help... They died for our country, and it behooves upon us to continue the help when they were alive as they are now in heaven," said Duterte.

"Dito sa panahon ko (during my term), I assure you that I will add more benefits for your family... Actually very important really is the family you leave behind will have the same privileges," he added.

Duterte, who steps down in June next year, said he hopes government would finish an insurance system and a bank exclusive to the military "before I make my exit."

He said government would lease "a part of Bonifacio to raise the money." It was not immediately clear which area he was referring to.

"Baka ako maiwan, gusto kong maglagay ng malaking pera sa Armed Force of the Philippines. 'Yan lang ang mabawi ko sa sundalo, lalo na 'yong namatay... their families will be protected, their families will be comfortable at 'yong (the) daily living at education of the children will be assured," the President said.

(Before I leave, I want to allocate funds to the Armed Force of the Philippines. That is the only thing I can do for soldiers, especially those killed.)

Duterte conferred the Order of Lapu-Lapu Rank of Kampilan to the wounded soldiers, and the Order of Lapu-Lapu with the Rank of Kalasag to their slain comrades.

Security forces on Monday searched among coconut trees for the flight data boxes of the aircraft involved in one of the country's worst military air disasters.

The plane "skidded" and burst into flames in a village, killing at least 50 people including 47 military personnel and 3 civilians. Another 53 were injured, most of them soldiers. It was not clear if the pilots were among the survivors.

The 3 civilians killed were not on the flight and had been working in a quarry, village leader Tanda Hailid told AFP.

Military spokesman Major General Edgard Arevalo said authorities have secured the crash site and would ensure militants on the island do not disrupt search efforts.

Dental records were being used to help identify the charred remains of victims.

C-130s have been the workhorses of air forces around the world for decades, and used to transport troops, supplies, and vehicles.

The second-hand Hercules that crashed Sunday was acquired from the United States and delivered to the Philippines earlier this year.

It was one of four in the country's fleet and was in "very good condition", the military said. Two others are being repaired while the third has been grounded following the crash.

"These are all seasoned and experienced pilots, that's why we are also unable to immediately say how this... (happened)," said Arevalo.

"Even if these (military assets) are not brand new... these are airworthy."

"This ranks as the worst crash of a Philippine military aircraft with 50 dead so far as compared to the 40 dead in a 1971 crash of a PAF C-47," Jose Antonio Custodio, a military historian and analyst, told AFP.

It was the latest in a series of recent military air accidents in the Philippines.

Last month, a Black Hawk helicopter went down during a night-time training flight, killing all six on board. The accident prompted the grounding of the country's entire Black Hawk fleet.

President Rodrigo Duterte's spokesman Harry Roque said Monday the incidents would provide "impetus for further modernization" of the armed forces.

"The whole country is mourning," he said.

— With reports from Jamaine Punzalan, ABS-CBN News; Agence France-Presse