The arrest of an Afghan asylum seeker suspected of killing two people in a knife attack targeting children in a German park has prompted calls for a much tougher migration stance and fired up campaigning for Germany's Feb.

A two-year-old boy and a man aged 41 have been killed in a stabbing in a German park. Police confirmed that a 28-year-old man from Afghanistan was arrested following the attack in Bavarian city of Aschaffenburg. Two others were taken to hospital with serious injuries and the public park was cordoned off by officers.

Police identified the suspect as an Afghan man. Politicians gearing up for an election responded with comments about migration and law and order.