On Thursday, the Washington Transit system voted to ban all issue ads after being asked to run an ad depicting a cartoon drawing of Mohammad. The ban was voted on and passed unanimously by the Washington Metropolitan Area Transit Authority. A spokesman said the ban "prohibits political, religious and advocacy ads through the end of the year."

The transit system had been asked by the American Freedom Defense Initiative to display the cartoon that won first prize at an event in Texas this month at which two gunmen opened fire near the venue and wounded a security guard before they were shot and killed by police.

The ad, which calls for Americans to support free speech, features a bearded, turban-wearing Mohammad waving a sword and shouting: "You can't draw me!"

In reply, a cartoon bubble portrays an artist grasping a pencil and saying: "That's why I draw you."

"There is nothing violent in that cartoon," Pamela Geller, founder of the American Freedom Defense Initiative said in an interview on Thursday. "If there is a group you cannot criticize ... it's the tyranny of that group."

New York Transit System also voted to ban all ads after they lost a court case when they refused to run an ad that read "Hamas Kills Jews."

"They are using their free speech to propagate misconception and to divide people along ethnic or religious lines," Nihad Awad, head of the Council on American Islamic Relations said. "It is up to the Metro authorities to deal with these hateful groups."