Image copyright Getty Images Image caption Canadian novelist Michael Ondaatje won the Booker Prize for his novel The English Patient

Six prominent writers are boycotting a major US literary event over plans to give satirical magazine Charlie Hebdo a freedom of speech award.

Authors including The English Patient writer Michael Ondaatje and Peter Carey will not attend the PEN Literary Gala in New York on 5 May.

They said PEN - known for defending imprisoned writers - was stepping beyond its traditional role.

Islamists stormed the Charlie Hebdo offices in Paris in January.

Twelve people were killed during the attack, over the magazine's depiction of the Prophet Mohammed.

Authors Rachel Kushner, Teju Cole, Taiye Selasi and Francine Prose are also against PEN handing the Freedom of Expression Courage Award to Charlie Hebdo, as they are uncomfortable with the magazine's "cultural intolerance".

'Moral obligation'

Booker Prize-wining author Carey told the New York Times that the group of writers felt PEN's role was to protect freedom of expression against government oppression.

"A hideous crime was committed, but was it a freedom of speech issue for PEN America to be self-righteous about?" said Carey.

"All this is complicated by PEN's seeming blindness to the cultural arrogance of the French nation, which does not recognise its moral obligation to a large and disempowered segment of their population."

The boycott has been criticised by the author Salman Rushdie, a former president of PEN who was in hiding for years over Islamist threats in response to his novel The Satanic Verses.

He said his friends were "horribly wrong" and he hoped nobody ever came after them.

Charlie Hebdo essayist Jean-Baptiste Thoret, who escaped the attack by arriving late to work, will accept the award on behalf of his colleagues.

PEN said it did not believe Charlie Hebdo's intent was to "ostracise or insult Muslims, but rather to reject forcefully the efforts of a small minority of radical extremists to place broad categories of speech off limits."

It added: "We will be sorry not to see those who have opted out of the gala, but we respect them for their convictions."