French prison officers blocked access to several jails around the country on Monday to demand tighter security after three officers were injured in an attack by a German terror convict last week.
The officers' unions say the blade attack by Christian Ganczarski, who is serving an 18-year sentence over the 2002 bombing of a Tunisian synagogue, illustrated the lax approach of prison authorities to violent convicts.
An anti-terror judge has charged Ganczarski with attempted murder for the attack on the officers, judicial sources told AFP late Monday.
At their protest prison guards used washing machines and a pile of burning tyres to block access to the high-security prison in Vendin-le-Vieil on the border with Belgium where he is being held.
Around 100 officers took part in the protest, an AFP journalist at the scene said.
In an apparent attempt to defuse the situation, the prisons service announced that the director of the facility had asked to be "relieved of his command" following calls by wardens for him to go.
Officers also demonstrated outside Fresnes prison south of Paris, one of France's largest where riot police were deployed, as well as in Marseille and Lyon.
A former top Al-Qaeda member, Ganczarski is accused of masterminding the 2002 suicide blast at an historic synagogue on the Tunisian island of Djerba, in which 21 people were killed. He was sent to jail in 2009.
He lunged at guards on Thursday after learning he might face extradition to the United States in connection with investigations into the September 11, 2001 attacks, according to union sources. The prison service said he was armed only with scissors and a razor blade.
Prison guards' unions said his detention conditions had recently been eased despite surveillance indicating he was planning an attack.
The outgoing head of the prison said Ganczarski had shown no signs of aggression.
Prison unions have called on guards to continue their blockage of jails on Tuesday.
On Saturday, trade unions walked out of talks with the justice ministry saying they had failed to receive a "concrete answer" to their demands to tighten security around dangerous inmates.
The prison where Ganczarski is being held will soon be housing Salah Abdeslam, the sole surviving suspect in the November 2015 Paris attacks which left 130 people dead.
Abdeslam will be moved to Vendin-le-Vieil from a prison south of Paris in February during his trial in Belgium over a shootout with police in that country.