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

Bondi Beach gunmen Sajid and Naveed Akram stayed at a hotel in the southern city of Davao for the entire time they were in the Philippines, according to staff.

The duo had listed Davao, a large city in the southern part of the Philippines on the island of Mindanao, as their destination. Their return flight was booked for Sydney.

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.

The shooting occurred on Sunday evening at Bondi Beach while a Hanukkah gathering was underway. Australian authorities said Sajid Akram, 50, and Naveed Akram, 24, opened fire using rifles, killing at least 15 people and injuring 42 others.

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

Sajid Akram, a gunman in the Bondi Beach shooting, had minimal contact with his Hyderabad family, who disowned him after his marriage. The family denies knowledge of his radicalisation, which investigators believe is unrelated to Indian influences.

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.

One of the alleged terrorists in Bondi’s terror attack was originally from India and had travelled back to his native country six times since migrating to Australia.

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.

Indian police said on Tuesday that one of the two gunmen behind Australia's Bondi Beach mass shootings, Sajid Akram, was an Indian citizen who had left the country 27 years ago.

Intelligence agencies revealed that one of the shooters in the Bondi Beach terror attack, Naveed Akram, came under police radar six years back in connection with a Sydney-based Islamic State cell.