Philippines National Police say they are investigating whether the father-son Bondi gunmen travelled to a region known as a hotbed for violent Islamic extremism.

Spending by Bondi shooters Sajid Akram and Naveed Akram in a Philippines terror hotspot should have been flagged by Australia’ financial monitoring system, industry sources say, with experts questioning how the men avoided raising the suspicion of intelligence agencies despite weeks on the ground.

Sajid and Naveed Akram returned to Sydney from Davao just around two weeks before the deadly mass shooting at Bondi Beach on December 14.

Sajid Akram and his son Naveed spent nearly the entire month of November in the Philippines, with the older man entering as an "Indian national", authorities in Manila said.

Philippines President Ferdinand “Bong Bong” Marcos Jr has dismissed as “misleading” claims the country is an “ISIS training hotspot” after his own immigration bureau confirmed the father and son Bondi Beach gunmen travelled to the southern province of Mindanao last month,

Naveed Akram, the surviving suspect in Sunday's mass shooting at Bondi Beach in Sydney, has been charged with 59 offences, including 15 counts of murder and one of committing a terrorist act, according to the New South Wales local court. The other gunman, his father Sajid Akram, 50, was killed in an exchange of fire with police at the scene.

The alleged gunman lost his job several months ago. His family said he pretended he was on a fishing trip for the weekend.

Fifteen people were killed and another 42 were injured when Sajid Akram and his son Naveed Akram, 24, opened fire with rifles on a Hanukkah event at Bondi Beach