The investigation codenamed "Heaven" went on for months before police in Berlin made the announcement Monday, Deutsche Welle reported.

Police said 1,700 people in Germany have been charged with possessing illegal material.

Using Internet Protocol addresses unique to each computer, thousands of other suspects were identified by investigators in 70 other countries, the report said.

The probe was sparked by a an unidentified German Internet service provider who called police when he noticed an unusual spike in data traffic and identified the target site, the report said.