Japanese police are investigating the case of a male worker at an affiliate of Amazon's Japan unit who allegedly sold child pornography through Amazon's website.

According to investigative sources, the man worked at Amazon Japan K.K.'s distribution center in Chiba Prefecture and was involved in product management and distribution.

The suspect, who is said to be in his 40s but has not been publicly identified, had been dispatched to the Amazon affiliate through an employment agency.

The case against him has been sent to prosecutors.

The suspect posted photo books of nude girls under 18 on the retailer's website, thus giving users of the Amazon website access to child pornography, police said.

Many of the photo books in question were returned to the distributor by customers who complained that they depict child pornography, the police said. But the suspect continued to allow the books to be sold on the website, police said, adding that the man admitted he was aware their sale was illegal.

The Aichi Prefecture Police launched an investigation last year after finding several books containing images of underage girls for sale on Amazon Japan's website.

Police have turned over to prosecutors documents regarding another man from the Kanto region who worked at a secondhand bookstore and who sold the photo books on Amazon's website.

Since November, police have raided Amazon's Tokyo headquarters and its distribution centers in Chiba and Kanagawa prefectures for evidence they broke laws banning the public display of child pornography.

According to Amazon Japan's guidelines, the company bans the sale of illegal products, stolen items and child pornography.