Paris ? School doors open for 12 million French children today, but there is far more at stake this year than back-to-school jitters.

An already contentious ban on Muslim head scarves and other religious signs faces its first test in France’s public schools — under the cloud of Islamic radicals holding two French hostages in Iraq to press their demand that the law be scrapped.

The law was one of the most divisive issues for the French in recent times, and no one was sure whether Muslim girls who cover their heads would defy it or compromise their beliefs to stay in school.

The law forbids all conspicuous religious signs or apparel in public schools, including Jewish skull caps and large Christian crosses. But it is aimed at Islamic head scarves and means to counter what many people fear is a rise in Muslim fundamentalism in schools.

Several Muslim organizations set up hot lines to counsel girls in a quandary over the law.

Sofia Rahem said her association, GFaim2Savoir, lingo for “I’m Hungry for Knowledge,” had received “an enormous number” of calls.

“They are young girls in distress who don’t know what to do with their future,” said Rahem, a 23-year-old university student who wears a head scarf. “They fear the return to school knowing they won’t be accepted with a scarf.”

Many Muslims feel their religion requires head scarves for female modesty, while some secular people see it as a symbol of Islamic militancy. Only a small minority of schoolgirls used the head scarf previously.

Muslim students gather in front of the Strasbourg Education Offices in eastern France to protest the law banning Islamic head scarves and other religious signs in public schools. The ban begins today as schools in France open.

The law, passed in March, brought heated arguments over religious freedom, free expression and France’s much cherished principle of secularism, which is seen by authorities as under threat. Officials contend the Muslim community is turning increasingly militant and is failing to integrate into French society.

France is home to an estimated 5 million Muslims, the largest Islamic community in western Europe.

French leaders refused to back down despite demands from the Islamic Army of Iraq, which is holding journalists Christian Chesnot and Georges Malbrunot. The group called the law an attack on Muslims.

Despite their disagreement with the law, many French Muslims appeared to support the government’s stand. A chorus of worldwide Muslim voices — from human rights groups to hard-line religious clerics — has pleaded for their release.

The Palestinian militant group Hamas, which claimed responsibility for deadly twin bombings in Israel on Tuesday, appealed for their freedom. Libyan leader Moammar Gadhafi said kidnapping foreigners in Iraq was “terrorism,” and Arab League Secretary-General Amr Moussa reiterated his plea for their release.