The incident took place in Borgo Prison on Friday morning, Prosecutor of Bastia City Caroline Tharot said, as cited by AFP.
She added that both guards had been transferred to a local hospital.
One of the prison guards was stabbed in the throat, the prosecutor added, without specifying the type of weapon used in the attack.
“This is a big attack. One of the two guards was left unconscious and the perpetrator is a prisoner who had already been on a special list for misconduct,” Maxime Coustie, a representative of a local prison union told AFP.
The detainee reportedly shouted “Allahu Akbar” while attacking the guards, Corse Matin newspaper said, citing an official from a local prison union.
The perpetrator was suspected of radicalization, France 3 reported, citing sources.
It’s not clear whether he was radicalized before being jailed or while serving his custodial sentence.
The man was serving a sentence for beating a man to death in a scuffle near a nightclub while intoxicated.
It comes days after similar assaults by inmates triggered protests by prison guards. Last week, a former senior Al-Qaeda member, 51-year-old Christian Ganczarski, attacked and injured guards with a scissors and razor blade at a high-security prison in Vendin-le-Vieil. Several days later, a convicted murderer attacked and injured several guards in Mont-de-Marsan jail.
The incidents triggered nationwide protests by prison guards, who have demanded better working conditions and tighter security.
On Thursday, more than 120 inmates at Fleury-Mérogis, the biggest prison in Europe, refused to return to their cells.
The French jail is notorious as a center of Islamic radicalization.