The prosecutor's office in the northern city of Hanover said that it had charged Sebastian Edathy, a former high-flying member of parliament known for his fight against far-right extremists on Tuesday.
"The former deputy is accused of downloading videos featuring child pornography onto his Bundestag laptop from the Internet on six days between November 1 and 10, 2013," it said in a statement.
It added that he was suspected of being in possession of a photo book and a CD deemed by prosecutors to contain illicit material featuring minors.
Edathy, 44, resigned citing health reasons in February after the allegations against him surfaced, touching off a major political scandal at the start of Merkel's third term.
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The case subsequently prompted a cabinet minister to resign under pressure over suspicions he leaked confidential information about the probe while he held the interior portfolio.
Edathy, who has not been remanded in custody and is reportedly lying low somewhere in southern Europe, had gained prominence for heading a parliamentary panel into the shock 2011 discovery of a neo-Nazi killer cell.