BRUSSELS — A month before the Paris terrorist attacks, Mayor Françoise Schepmans of Molenbeek, a Brussels district long notorious as a haven for jihadists, received a list with the names and addresses of more than 80 people suspected as Islamic militants living in her area.

The list, based on information from Belgium’s security apparatus, included two brothers who would take part in the bloodshed in France on Nov. 13, as well as the man suspected of being the architect of the terrorist plot, Abdelhamid Abaaoud, a Molenbeek resident who had left for Syria to fight for the Islamic State in early 2014.

“What was I supposed to do about them? It is not my job to track possible terrorists,” Ms. Schepmans said in an interview. That, she added, “is the responsibility of the federal police.”

The federal police service, for its part, reports to the interior minister, Jan Jambon, a Flemish nationalist who has doubts about whether Belgium — divided among French, Dutch and German speakers — should even exist as a single state.