A suspected right-wing extremist is under investigation on suspicion of attempted manslaughter after he allegedly used a shovel and beer bottles to attack a 13-year-old girl in an attack on a left-wing group's camp.

Prosecutor Hans-Manfred Jung in the city of Kassel says the 19-year-old man was arrested after the Sunday morning attack. The suspect's name was not released.

Jung says the girl was no longer in critical condition on Monday. She had been sharing a tent with her 23-year-old brother, who suffered light injuries in the assault.

Jung says participants of the summer camp — organized by the youth wing of the Left party — had demonstrated in a nearby town in central Germany against far-right violence the day before the attack.