An Australian man who allegedly sexually assaulted babies and children in the Philippines will face human trafficking and murder charges, prosecutors say.

The suspect, Gerard Peter Scully, 51, was arrested in the southern Philippines city of Malaybalay in January after allegedly sexually abusing at least eight girls, including an 18-month-old infant.

He also allegedly strangled one of the girls to death, with her skeleton later discovered buried under a house he had rented, investigators said.

• Accused Aust sex abuser investigated for murder

A complaint, filed by Justice Department investigators with the prosecutors’ office, said Scully forced the girls to perform sexual acts in front of a video camera for paying clients overseas.

“Let notice be served to these criminal elements that the days of their child cybersex operations are numbered,” Justice Secretary Leila de Lima said in a statement on the case on Thursday.

“Wherever these syndicates are, we will hunt them down and we will bring them to justice.”

Suspect, Gerard Peter Scully, 51, was arrested in the southern Philippines city of Malaybalay. Photo: AAP

In the complaint outlining the case against Scully, a 13-year-old girl was quoted as saying that her impoverished family agreed she could do domestic work at his home in 2012.

But she was instead forced to perform sex acts with other girls, and was beaten by Scully’s Filipina girlfriend when she refused, according to the prosecutors’ complaint.

“They told me they had to take pictures of me naked because there was an American who really wanted to see me naked … and because the American will pay a large amount,” the complaint quoted her as saying.

The girl said she fled Scully’s house after she learned he had sold her to a German national who was coming to collect her, the complaint said.

The head of the anti-human trafficking division of the justice department’s investigating arm, Eric Nuqui, said Scully had been the subject of an international probe after Dutch police found out about his activities.

If convicted, the Australian could face life in prison.

The Philippines is a major hub of a billion-dollar global child cybersex industry, with operators aided by widespread poverty and legal loopholes that allow them to remain anonymous.

Last year, de Lima said online child abuse was the leading cyber-related crime in the Philippines, making up 46 per cent of the more than 200 cases handled by law-enforcement agencies.