French police have charged two radicalized prison inmates with plotting terrorist attacks – within days of their scheduled release.

In the first such case in the history of French anti-terrorism the men, who were radicalized behind bars while serving time for non-terrorist crimes, are due to be released from Fresnes prison, just south of Paris, next week.

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French TV news station LCI report that the men had plotted attacks against numerous targets including prison guards while they were in prison and police officers at a police station after they were released.

French intelligence services had been watching the two men for several months.

Cameroonian Charles-Henri M. was reportedly the mastermind behind the potential attacks. The 28 year old was an Islamic State (IS, formerly ISIS/ISIL) sympathizer. His accomplice was 22-year-old Frenchman Maxime O, who is also a radical Islamist.

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France 24 reports that the pair were also planning to use methods including hostage-taking and gun attacks.

The investigation began last December after a phone containing details of a plot to murder “disbelievers” was found in Charles-Henri’s cell.

Charles-Henri M. was incarcerated for robbery in 2013 and was due to be released on Tuesday. Maxime O. was jailed for attempted murder in 2014, he was due to get out next week.

230+ killed in attacks on France since 2015, more than previous century of terrorism https://t.co/wDdcEkMW77 — RT (@RT_com) July 15, 2016

While being questioned by police LCI report that Charles-Henri praised his “brothers” who carried out the terrorist attack in the Bataclan theatre in November 2015. He also admitted to plotting attacks.

France has been in a state of emergency since 130 people were killed in terrorist attacks, one of which targeted the Bataclan, in Paris in November 2015. The country has suffered several smaller attacks since then.