France's attempts to de-radicalise homegrown Islamist extremists in the wake of terror attacks has been pronounced a "total fiasco" in need of a complete overhaul in a damning parliamentary report.

President François Hollande launched the drive to reverse radicalisation among thousands of French Muslims in the wake of terror attacks that have killed 238 people since January 2015.

However, the report, by a cross-party senate committee, was denounced as an amateurish flop this week, accusing the government of funding "pseudo-experts" who pocketed millions of euros with few tangible results.

Among the damning revelations in the report were the fact that the only de-radicalisation centre currently up and running, and fully staffed at an annual cost of €2.5 million, is in fact empty.

Twelve other centres slated to be set up have not been opened.