Law enforcers acting on a tip-off from the US Department of Homeland Security raided several suburban Manila homes last weekend, the National Bureau of Investigation said.
"We were able to rescue two girls who were not quite eight years old," Eric Nuqui, head of the bureau's anti-human trafficking division told AFP.
"They were made to do sexual acts with minors as well as adults. These include intercourse as well as acts involving sex toys."
Data from computer storage devices seized from the alleged Filipino operators, two men and two women, indicate at least six other children were victims of abuse, Nuqui said.
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The bureau is trying to find these children as well as possible accomplices of the suspects, now held without bail for qualified human trafficking and rape, he added.
"These children are all from extremely poor families or broken families," Nuqui said, adding that parents will also be investigated to check if they were complicit in the crimes.
Last year, online child abuse was the leading cyber-related crime in the Philippines, making up 46 percent of the more than 200 cases being handled by law-enforcement agencies, according to the justice department.
Filipino police last month arrested an Australian man, Gerard Peter Scully, 51, after he allegedly sexually abused at least eight girls, including an infant in front of a video camera, for clients overseas.
He is also accused of murdering one of the victims.
Danish police arrested 10 male suspects in yesterday's raids, they said.