Battle-hardened French Islamic militants who have fought in Iraq are returning home with the ability and desire to carry out attacks in Europe, posing a “very worrying” new terrorism risk, a senior French anti-terror judge said today.

French security service agents apprehended 13 suspected militants, including one about to flee the country, in a dawn raid today that was launched to track down the perpetrators of a terrorist attack in Morocco last year.

French anti-terrorist police arrested at least four people today in connection with a planned attack on the US embassy in Paris and other American interests in France, police said.