French satirical magazine Charlie Hebdo received a freedom of expression award on Tuesday at a gala US ceremony boycotted by some leading authors in protest at the publication's lampooning of Islam.

Security was tight at the PEN America ceremony in New York, which came 48 hours after an attack targeting a Texas venue that featured a contest to draw the Prophet Mohammed.

Police officers armed with semiautomatic weapons stood guard outside the American Museum of Natural History, where the award was conferred by the literary and campaigning group during a dinner.

Officers also patrolled with dogs outside the building, near Central Park, and guests had to pass through metal detectors.  

Charlie Hebdo was hit by a militant attack in Paris in January after regularly publishing caricatures of the Prophet Mohammed. Twelve members of its staff were shot dead.

Chief editor Gerard Biard told the New York ceremony that he was "very proud" to accept the award, and urged others to espouse the magazine's values in support of freedom of conscience.

"Each citizen of the world must adopt these values and stand up for them, against political and religious obscurantism. The more numerous we are, the weaker they are," he said.

The PEN ceremony was shunned by several high-profile writers including Peter Carey, Michael Ondaatje and Francine Prose, arguing that Charlie Hebdo was offensive to France's minority populations.

"A hideous crime was committed, but was it a freedom-of-speech issue for PEN America to be self-righteous about?" Carey told the New York Times in advance of the ceremony.

"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."

Some 200 of PEN's 4,000 members signed a letter protesting against the choice.

That attracted scorn from others such as author Salman Rushdie, who lived in hiding for a decade under threat of an Iranian death sentence for alleged blasphemy in his novel "The Satanic Verses."

Rushdie has been issuing caustic denunciations of the boycott lobby on Twitter, and at the ceremony he told AFP: "It's important to continue to defend the right of free expression."

PEN said it did not believe Charlie Hebdo's intent was to "ostracize 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."

In Texas on Sunday, two gunmen were shot dead by police as they tried to storm the cartoon drawing event. The Islamic State group has claimed responsibility, although US officials caution it is too early to draw a firm link.

Biard has rejected any comparison between the shootings in Texas and his magazine's work, distinguishing between an event organised by an anti-Islamic group and Charlie Hebdo's right to ridicule anyone it sees fit.