BERLIN - German Interior Minister Thomas de Maiziere on Thursday said he is shocked receiving allegations that Berlin state government had tried to cover up their misconducts after the terror attack on Berlin's Christmas market last year.

De Maiziere said the allegation "unheard of" and expected everyone involved "thorough and transparent explanation", Deutsche Welle cited his words as reporting.

Berlin State Interior Minister, Andreas Geisel, disclosed earlier that Berlin office of criminal investigation (LKA) could have prevent the terror act on Berlin's Christmas market, which killed 12 people and injured over 50.

Geisel said LKA had sufficient evidence to arrest the attacker, Anis Amri, on drug charges weeks before he drove his truck into the crowds. After committing the terrible massacre, Amri fled to Italy and there he died in a shootout with the local police.

LKA had tapped Amri's phone through June 2016, so they had the chance to catch him, Geisel noted.

These details were, however, not disclosed to public before and there were reasons to suspect an extensive cover-up relating to Amri, Geisel said.

De Maiziere on Thursday said he have "all respect for the decision to make the matter public."