Gunmen have killed at least twelve people, after attacking the offices of a magazine that published a cartoon of a gay Muslim kiss.

Masked attackers stormed the Paris offices of satirical magazine Charlie Hebdo this afternoon.

The gunmen opened fire with assault rifles while staff were in an editorial conference, killing at least twelve people, and injuring another seven.

The magazine has repeatedly mocked Islam, publishing an edition “guest edited” by the Islamic prophet Muhammad in 2011.

The magazine has previously been targeted with fire-bombs and cyber-terrorism for its controversial content.

An edition after a previous attack included a poignant picture of the magazine’s editor kissing a Muslim man, with the message: “Love is stronger than hate.”

The French President Francois Hollande has condemned the “exceptional barbarity” of the attack, which he labelled an affront to free speech.

Prime Minister David Cameron said: “The murders in Paris are sickening. We stand with the French people in the fight against terror and defending the freedom of the press.”

A message previously left on their website after an attack said: “You keep abusing Islam’s almighty Prophet with disgusting and disgraceful cartoons using excuses of freedom of speech… Be God’s Curse On You! We Will be Your Curse on Cyber World!”

More to follow.