Paris (AFP) - French satirical weekly Charlie Hebdo published a provocative front-page cartoon about Islam and the recent terror attacks in Spain on Wednesday, sparking fears that it could encourage Islamophobia.

The latest edition of the magazine, which was targeted by Islamist gunmen in 2015, shows two people lying in a pool of blood after being run over by a van next to the words, "Islam, eternal religion of peace."

A dozen extremists of Moroccan origin are believed to have plotted last week's attacks in Barcelona and Cambrils, where 15 people were killed and more than 100 injured after the assailants drove a van and car into crowds.

Investigators think the attackers were radicalised by an extremist Islamic preacher who died in an explosion while the group was trying to produce explosives.

Critics of Charlie Hebdo saw its front-page cartoon as tarring an entire religion, practised by around 1.5 billion people worldwide, by implying it is inherently violent.

As the cartoon became one of the top trending topics on Twitter in France -- with more than 15,000 tweets praising or criticising it -- prominent Socialist MP and former minister Stephane Le Foll called it "extremely dangerous".

"When you're a journalist you need to exercise restraint because making these associations can be used by other people," he said.

Charlie Hebdo editor Laurent "Riss" Sourisseau defended the choice in an editorial, saying that experts and policy-makers were avoiding hard questions out of concern for moderate law-abiding Muslims.

"The debates and questions about the role of religion, and in particular the role of Islam, in these attacks have completely disappeared," he wrote.

Charlie Hebdo lampoons all religions and religious figures, but its depictions of the Prophet Mohammed -- an act considered sinful under Islam -- sparked outrage, death threats and ultimately violence.

Two gunmen who claimed allegiance to Al-Qaeda killed 12 people in an attack on its offices in January 2015 which left many of its star cartoonists dead.

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Hundreds of thousands of people marched through the streets of France afterwards, rallying behind the slogan "Je Suis Charlie" ("I Am Charlie") in defence of the right to free speech.

Riss said in the wake of the violence that the magazine would stop depicting the prophet, leading one top journalist to quit and accuse its new management of going soft on Islamist extremism.

Patrick Pelloux, a former Charlie Hebdo contributor, defended the paper, saying: "We need to fight Islamist terrorism and religious radicalism, not a magazine."