German police have carried out raids across Berlin on properties linked to a mosque used by the Christmas market truck attacker, Anis Amri.
A 460-strong police deployment searched apartments and two commercial premises. Six prison cells were also searched.
The organisation which ran the mosque has been closed down.
Twelve people were killed and more than 50 injured by Amri, a Tunisian asylum seeker, in December. He was shot dead by police after fleeing to Italy.
Police say the raids follow a decision to ban the organisation, known as Fussilet 33, in mid-February. The properties targeted were used by those who ran the organisation, police said.
German prosecutors say that Amri visited the mosque frequently, including on the day of the attack.
It is alleged to have been a centre for radicalising Muslim recruits for so-called Islamic State in Syria and collecting funds for IS attacks.
Police said they had kept watch on the building with a camera positioned opposite the entrance. The mosque closed down a week ago.
Amri carried out his attack on 19 December at the market in central Berlin. He hijacked the lorry after killing its Polish driver before ploughing through the stalls. Eleven people were killed there.