France's anti-terrorism prosecutor says about 40 convicted terrorists are due to be released from French prisons this year and next, calling the entry back into society of the unrepentant ones a 'major risk.'

Francois Molins said on BFM television today that France still faces a significant threat from homegrown supporters of the struggling Islamic State group. Molins estimated that 600 to 700 French extremists are unaccounted for in the areas of Iraq and Syria claimed by IS, though many have probably been killed.