Picket lines have been set up outside 119 prisons across France as prison guards continued a nationwide protest over working conditions.
A spokesman for the penitentiary administration said the situation had "heavily deteriorated" in 45 prisons because of guards blocking entrances.
Talks between justice ministry officials and prison guard unions yesterday failed to find a solution to the stand-off, now in its second week.
The protests, which have been fuelled by inmate attacks on guards, are threatening to disrupt the first trial related to the deadly Islamic State attacks on Paris in 2015.
Jawad Bendaoud, who is accused of helping two of the attackers, is scheduled to travel from the Fresnes prison south of Paris to appear in court today.