Has French secularism encouraged Islamic militancy?

Police say 12 people have been killed and 10 others injured in an attack by masked gunmen at the offices of the French satirical magazine Charlie Hebdo.

Three gunmen, believed to be Islamic militants, are thought to be behind the attack.

But what will the attack mean for a country with the largest number of Muslims in western Europe?

Katie Razzall reports for BBC Newsnight.