Mourners laid flowers near the scene of the deadly Christmas market attack on Monday as investigators puzzled over the motive of the suspect and fears swirled that the rampage could deepen divisions in German society.

Thousands of people in Magdeburg formed a human chain on Monday to remember the victims of the attack on a Christmas market in the central German city, as the far-right Alternative for Germany (AfD) held a rival rally.

As a nation mourned, with citizens leaving flowers and lighting candles in Magdeburg where the incident took place on Friday, questions swirled about whether more could have been done and whether the authorities could have acted on warnings.