BERLIN (AP) — German prosecutors say they've thwarted an Islamic extremist plot to launch an attack with the deadly toxin ricin.

Federal prosecutors said Thursday a 29-year-old Tunisian, identified only as Sief Allah H., who was arrested Wednesday, started procuring material online including seeds needed for the creation of ricin in mid-May.

They say he succeeded in creating the toxin this month and investigators found it in a search of his Cologne apartment.

They're still investigating exactly how the suspect planned to use the toxin, but said he was working on an attack in Germany.

Prosecutors say they currently have no evidence of a connection with any extremist organization.

They didn't immediately comment on a Bild newspaper report that American intelligence tipped off German investigators.