French prosecutors credited recently enhanced surveillance powers for allowing them to foil a planned terror attack directed by Islamic State targeting sites such as Disneyland Paris. Paris prosecutor François Molins said Friday “new techniques” granted under an anti-terror law, which went into effect this summer helped investigators track down a group of militants who he said were “remotely controlled” by a commander in Islamic State territory in Iraq or Syria. The militants received instructions on how to procure themselves weapons via encrypted messages, Mr. Molins said. The enhanced surveillance powers, granted in the wake of the Nov. 13, 2015, attacks that killed 130 people, have rankled civil-liberties groups. Critics have protested the country’s state of emergency, which has been in effect more than a year, and say that the wording of new laws could allow the new measures to be used more widely than terrorism investigations.