German prosecutors say they have indicted a 35-year-old Islamic extremist for planning to carry out a bomb attack.

Frankfurt prosecutors say the Turkish and German citizen, whose name wasn't given, was charged with preparing an act of violence, forging documents and violating weapons and explosives laws.

He faces up to 10 years imprisonment if convicted.

The man was arrested in April in Oberursel, near Frankfurt, together with his wife, who has since been released, on suspicion they were plotting to attack a May 1 cycling race.

Authorities seized a cache of weapons, including a pipe bomb and chemicals that can be used to make explosives at their home.

Prosecutor Nadja Niesen said Wednesday investigators were unable to confirm that the man planned to attack the race.