Police in the German capital Berlin are hunting for a Tunisian national in connection with Monday's attack on a Christmas market that killed 12 people and injured 48.

German news magazine Der Spiegel [der SHPI-gull] has reported that police found an identity document in the truck under the name "Anis A," born in the Tunisian city of Tataouine in 1992. Other reports suggested that the man was known by three different names.

Police said earlier they had received more than 500 tips about the attack as of Tuesday night, but it wasn't clear whether prosecutors had any concrete leads.

Following the incident, a Pakistani man was detained based on a description from witnesses of a suspect who had jumped from the truck and fled. He was later released due to a lack of evidence. Islamic State has claimed responsibility for the attack.