PARIS (AP) — French authorities have received 9,000 tips related to Islamic extremism through a dedicated hotline and a website, President Francois Hollande said Thursday.

French officials believe some 600 Muslims have left the country for Syria and Iraq, but the president's comments about thousands of tips offer a hint of the scale of the concern over religious radicalism in France. Hollande was quick to note that not all the tips were linked to genuine dangers, but said it was a sign that France needed a program to fight extremism.

"We should create de-radicalization centers," he said.

The period during which the tips were made wasn't made clear, although a hotline has been active in some form since 2014.

Hollande was speaking during a televised exchange with Veronique Roy, whose son is believed to have died in Syria after converting to a radical form of Islam.

Roy was one of four citizen panelists brought as part of a town hall-style question-and-answer session at Paris' Museum of Man.

Hollande also tackled the issue of immigration, saying that what the French government needed to do for the migrants at Calais hoping to get to Britain "is to convince them that they won't pass."