The Paris prosecutors' office says an investigation has been opened after one of the hostages in the January attacks around Paris accused some television and radio stations of having put his life in danger and sued them.

Twenty people were killed, including the three attackers, in the Islamic extremist attacks around Paris that ended with police raids on a printing plant and a kosher supermarket where hostages were being held.

At the printing plant north of Paris, hostage Lilian Lepere was hiding in a cupboard under a sink, apparently unknown to the gunmen, when at least three television and radio stations revealed his possible presence. He was eventually released unharmed.

Lepere's lawyer, Antoine Casubolo Ferro, told The Associated Press that the complaint aims to increase media awareness of life-threatening situations.