The law envisages several scenarios, says Francois Michaud-Nerard, head of funeral services for the city of Paris.
"Either the families ask for their remains or they don't. If the families ask for their remains, the deceased have the right to a burial in the place where they lived, or where they died, or where the family has a burial plot."
In any case, even "if there is no obligation to have an anonymous grave, that would be in everybody's interest," he said.
Officials fear that such a grave could become a site of "pilgrimage" for other extremists.
Also Read
Seven gunmen and suicide bombers were killed on November 13 but so far, only four of them have been formally identified.
Of the three who blew themselves up outside the Stade de France national stadium in Saint-Denis, one has been identified as French-born Bilal Hadfi, 20, who lived in Belgium. The other two remain unidentified, despite carrying Syrian passports registered as entering Greece in October in the names of Ahmad al-Mohammad and Mohammad al-Mahmod.
Three other people were killed in a massive police assault on a flat in the northern Paris suburb of Saint-Denis. One was Belgian jihadist Abdelhamid Abaaoud, 28, the suspected ringleader of the attacks, while another was a French-born woman of Moroccan descent identified as his cousin, 26-year-old Hasna Aitboulahcen.
A third man who blew himself up during the raid has not yet been identified.
Alexandre Luc-Walton, lawyer for the Amimour family, said his clients "were waiting for news from the forensic institute. They still do not have permission to bury him.