French Prime Minister Jean Castex on Wednesday defended draft legislation aimed at clamping down on radical Islamism as a "law of freedom" after a torrent of criticism from Muslim countries and expressions of concern from the US.

"This bill is not a text aimed against religions or against the Muslim religion in particular," he told reporters after the cabinet approved a text to present to parliament. "It is the reverse -- it is a law of freedom, it is a law of protection, it is a law of emancipation against religious fundamentalism."

The legislation had been criticised by Muslim leaders including Turkish President Recep Tayyip Erdogan while on Tuesday the US envoy on international religious freedom said he was concerned by the bill.