An Islamic State leader linked to the 2015 attack on the French satirical newspaper Charlie Hebdo was killed in a US airstrike in Syria, US military officials said on Friday.

Boubaker al-Hakim was killed in Raqqa on November 26, officials said. He is believed to have played a role in Islamic State attack planning. The officials weren't authorised to discuss the strike publicly and spoke on condition of anonymity.

Al-Hakim, a 33-year-old French Tunisian, was a mentor to the brothers who gunned down cartoonists at the French paper on January 7, 2015.

He was arrested in Syria and sent to France, where he was convicted in 2008 and sentenced to seven years in prison. He was considered at the time to be among the most radicalized of the network of young extremists from the Paris area, which included the brothers Said and Cherif Kouachi.