The suicide bombing carried out by a Syrian refugee in southern Germany was "likely" to have been an Islamist attack, the Bavarian Interior Minister has said, as he admitted the incident raised serious questions about the country's asylum laws and national security.

German newspaper Die Welt quoted Bavarian Interior Minister Joachim Herrmann as saying: "My personal view is that it is unfortunately very likely that a real Islamist suicide attack took place here."

And he later told Reuters that the recent attacks raised serious questions about Germany's asylum law and security nationwide.