German authorities say they have arrested an acquaintance of the suspected Berlin Christmas market attacker, Anis Amri, in a separate case.
Frauke Koehler, a spokeswoman for federal prosecutors, said on January 4 the authorities were investigating whether he played a role in the truck attack that killed 12 people in the German capital before Christmas.
The spokeswoman said that the 26-year-old Tunisian, whose name wasn't disclosed, had known the main suspect and fellow Tunisian Amri since the end of 2015 and the pair ate together at a restaurant the night before the December 19 attack.
Koehler said the man's accommodation was searched by police on January 3.
"We are investigating him for possible participation in the attack," the spokeswoman told reporters, adding there was not sufficient evidence at this point to charge the man for any role in the attack.
However, local prosecutors in Berlin said in a separate statement that they detained the man on December 3 evening for fraud involving social benefits.
Amri, 24, was killed in a shoot-out with Italian police in a Milan suburb after they stopped him for a routine identity check on December 23.
The Islamic State extremist group claimed responsibility for the Berlin attack.
Based on reporting by AP and Reuters