French police are investigating death threats made against satirical magazine Charlie Hebdo over a cartoon of Islamist scholar Tariq Ramadan, who despite facing rape allegations continues to teach at Oxford University.

The provocative magazine was the target of a deadly jihadist attack in January 2015 after publishing cartoons of the Muslim prophet Mohammed.

On the cover of its edition published last Wednesday, Mr. Ramadan is depicted in an explicit pose, with the caption: “I am the sixth pillar of Islam.”

The five pillars are faith, prayer, charity, fasting, and pilgrimage to Mecca. Many Sunni scholars consider jihad, or holy war, as the sixth pillar of the faith.

Swiss national Mr. Ramadan, 55, is a lecturer at Oxford University and a controversial figure in France where he represents conservative Islam and soft Islamism.

His grandfather founded the Muslim Brotherhood in Egypt and his father was a senior figure in the organisation, which pushes for a global caliphate ruled by Islamic law.

He is under investigation after being accused of rape by two women after the Harvey Weinstein scandal sparked a wave of sexual abuse accusations around the world.

Sexual assault claims are a "Zionist plot" 🙄 https://t.co/en29D1epek — Breitbart London (@BreitbartLondon) October 30, 2017

Laurent ‘Riss’ Sourisseau, Charlie Hebdo‘s editor, said the threats and hate mail had “never really stopped” after the 2015 jihadist attack in which 12 people were gunned down at its offices.

“Sometimes there are peaks when we receive explicit death threats on social media – this has been the case once again,” he told Europe 1 radio.

However, he suggested the climate had worsened. “Calls to murder have become commonplace,” he said.

“It’s always difficult to know if these are serious threats or not, but as a principle, we take them seriously and press charges.”

Jean Plantureux, one of France’s most famous satirical cartoonists, added: “It’s great this drawing. I don’t see what people have against it. He’s got a big d*ck and says I’m the sixth pillar of Islam. They’re just having a bit of fun.”