Around 100 militants who fought with rebel groups in Syria and Iraq have returned to France, requiring "massive" resources for surveillance and other security measures to prevent attacks, a French lawmaker said on Friday. Thousands of Western volunteers have traveled to Syria and Iraq to join Islamist fighting groups, **tably Islamic State. Of an estimated 1,000 volunteers who left from France - the top source of Western volunteers for the Islamist jihad in the region - around 100 have returned and are currently in the country, Socialist lawmaker Sebastien Pietrasanta told Reuters.