Bangkok: Australian Federal Police have played a key role in uncovering a syndicate streaming extreme child sex and torture to Australian paedophile predators in a $1 billion-a-year underground industry in the Philippines.

A Queensland man has been arrested and other arrests in Australia are expected after authorities in the Philippines rescued three sisters aged eight, nine and 12 and an 11-year-old girl, based on information partly provided by the AFP.

The mother of the sisters and two other women have been arrested and charged with human trafficking, child abuse and forcing the girls to engage in explicit sex acts.

The children are being cared for in a shelter for abused children in Bacolod City, 720 kilometres south of Manila, where the offences allegedly took place.