Among those arrested were two minors and two people considered mentally handicapped, national police officials said in a statement.
The suspects had exchanged the pornographic photographs and videos of children online and "some of the images seized by police are extremely harsh and show sadism and bestiality," the statement said.
The child pornography investigation began with "cyber-patrols" on the Internet by specialised agents, who after about a year were able to identify dozens of suspects.
Around 300 police participated in the raid across 28 provinces, searching the homes of the suspects and seizing, in addition to the images, equipment such as computers and photo and video cameras.