A book written by the late editor of French satirical weekly Charlie Hebdo, Stephane Charbonnier - known as Charb - is set to be published posthumously.

The book, which upholds the right to ridicule religion, was finished two days before Charb was killed by Islamic militants in January, publishers say.

It argues that the fight against racism is being replaced by a misguided struggle against "Islamophobia".

Charb and 11 others were killed during a Charlie Hebdo editorial meeting.

The attack on the Paris offices of the newspaper was carried out by two brothers, Said and Cherif Kouachi, who were later shot dead by police.

Charb had received numerous death threats following Charlie Hebdo's publication of cartoons featuring the Prophet Muhammad in 2006. The magazine's offices were firebombed in 2012.

Charb's book - which goes on sale on Thursday - is entitled An Open Letter to the Fraudsters of Islamophobia who Play into Racists' Hands.

It is both a defence of Charlie Hebdo's editorial stance and an attack on the paper's detractors.

"The suggestion that you can laugh at everything, except certain aspects of Islam, because Muslims are much more prickly that the rest of the population - what is that, if not discrimination?"

He condemns this position as "white, left-wing bourgeois intellectual paternalism".

Charlie Hebdo, which was launched in 1969, poked fun at conservatives and all religions. It had a small circulation and folded in 1981, but was resurrected in 1992.