This article is more than 9 years old

This article is more than 9 years old

David Letterman has been targeted by a prominent jihadist internet forum which has called on radical Muslims to "cut the tongue of" the popular US late-night comedian.

A contributor to the shumukh al-Islam online forum claimed Letterman had insulted Osama bin Laden and another senior al-Qaida leader Ilyas Kashmiri in a skit on his late night CBS show.

The contributor, who called himself Umar al-Basrawi, made the online comment in response to a gesture he claims that Letterman made where he "put his hand on his neck and demonstrated the way of slaughter" during a comedy skit.

Letterman is supposed to have made the gesture on his show following the announcement on 5 June that a drone strike in Afghanistan had killed Kashmiri.

"Is there not among you a Sayyid Nosair al-Mairi," Al-Basrawi wrote on the forum, referring to the man convicted of the 1990 killing of Meir Kahane, the founder of the Jewish Defense League. "To cut the tongue of this lowly Jew and shut it forever?"

The call to attack Letterman, who is not Jewish, was discovered by The Site Monitoring Service, a private intelligence network that advises the US government on threatening online material.

The shumukh al-Islam forum is a popular online destination for radical Muslims and is often used by al-Qaida, said Adam Raisman, analyst at The Site Monitoring Service.

The FBI said it was taking the threat seriously. Executives at broadcaster CBS and a spokesman for Letterman both declined to comment on the threat.

Letterman has been the target of criminal threats in the past. A former CBS News producer was jailed for trying to extort $2m from Letterman in 2009 by threatening to expose the host's sexual dalliances with members of his staff.

A former painter at Letterman's ranch in Montana was jailed following a 2005 plot to kidnap the TV funnyman's nanny and son.

A radical Muslim group last year warned the creators of South Park they could face violent retribution for depicting the prophet Muhammad in a bear suit on the Comedy Central cartoon.

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