A Christian preacher is among eight men charged over the abuse of a 13-year-old girl, who was allegedly sexually exploited by her father over two years.

Police claim seven men made contact over the internet with the father who then organised for them to meet his daughter at various locations in Western Australia where the offences were committed.

The men face a total of 503 charges for offences that allegedly happened when the girl was aged between 11 and 13.

She is now safe and in care, receiving treatment.

Child sex abuse detectives arrested the Perth father and the seven others after a tip-off from the public in April.

The alleged offenders include 41-year-old Pastor David Volmer from Banksia Grove, who pleaded guilty in the Perth Magistrates Court earlier this month to 12 child sex abuse charges.

Detective Superintendent Glenn Feeney said the offenders lived in different suburbs and the only common factor between them was that they knew the father.

Det Supt Feeney gave an example of the "horrific" nature of the offences, saying one man was in possession of 200,000 videos and four million child pornography images.

Of those videos and images, 149 were of the victim.

Det Supt Feeney said the investigation, dubbed Operation Ripstop, was ongoing and the material seized would be used to target other predators.

"It's disgusting material - there are no words to describe it," he said.

"Any sex offence against a child is just beyond words."

The father, who cannot be identified because it could identify his daughter, has been charged with 228 offences including sexual servitude of a child and stupefying with intent to commit an indictable offence.

Volmer was the executive director of the WA Prison Fellowship, a religious program for inmates.

The married father of two young daughters has previously lived in the US and Singapore.

The other accused men are 35-year-old Nicholas Adam Beer from Wanneroo, 41-year-old Troy Phillip Milbourne from South Bunbury, 42-year-old Ryan Trevor Clegg from Attadale, 45-year-old Alfred John Impicciatore from Wembley, 47-year-old Mark Wesley Liggins from Coodanup and 47-year-old Benjamin Simon Clarke from Bedfordale.