The chancellor said Tuesday she was relieved Andreas Hollstein, the mayor of Altena and a member of Merkel's conservative party, was back home with his family after the attack Monday night, AP reported.
Hollstein became known nationally for his welcoming policies toward asylum seekers.
Local media reported an allegedly drunk German man asked Hollstein at a kebab restaurant in Altena if he was the mayor and then stabbed him. Hollstein was taken to the hospital but released late Tuesday.
Armin Laschet, the governor of North Rhine-Westphalia state where Altena is located, said "the security agencies assume the attack has a political background."