The new edition of the French satirical magazine Charlie Hebdo has gone on sale, with a cartoon depicting the Prophet Muhammad on its cover. Three million copies are being printed - a week after Islamist gunmen murdered eight journalists at the magazine and four other people in Paris. The cartoon shows the Prophet weeping while holding a sign saying "Je suis Charlie" (which translates to "I am Charlie"). It is believed earlier cartoons of the Prophet prompted the attack. The slogan "I am Charlie" has been widely used following the shootings.