One of the world's biggest international darknet platforms for child sexual abuse images has been busted with more than 400,000 users, German prosecutors have said.

Four suspects from Germany were arrested in connection with the "Boystown" darknet site, which paedophiles used to exchange and watch indecent images of children and toddlers from all over the world, according to authorities.

Frankfurt prosecutors said they found images of the "most severe sexual abuse of toddlers" among photos and video material on the platform, which has been active since at least 2019.

Three suspects, who were said to be the administrators of the online platform, were arrested in mid-April in along with an alleged prolific user of the site.

One of the suspects was arrested in Paraguay.

Authorities said their investigation involved "one of the world's biggest child pornography darknet platforms".

A German police task force investigated the platform, its administrators, and users for months in co-operation with Europol and law enforcement authorities from the Netherlands, Sweden, Australia, the United States, and Canada.

The suspects included a 40-year-old man from Paderborn, a 49-year-old man from Munich and a 58-year-old man from northern Germany who had been living in Paraguay for many years, the prosecutors' statement added.

They allegedly worked as administrators of the site and gave advice to members on how to evade law enforcement when using the platform.

A fourth suspect, a 64-year-old man from Hamburg, is accused of being one of the most active users, having allegedly uploaded more than 3,500 posts.

Germany has requested the extradition of the suspect who was arrested in Paraguay.

No names were given in line with Germany privacy regulations.

After raids of several buildings in German in mid-April, the online platform was shut down.