Washington D.C. transit officials voted Thursday to suspend all issue-oriented advertising on the city's rail and bus system after the agency was asked to consider an ad featuring an image of the Muslim prophet Muhammad. 

The Washington Metropolitan Area Transit Authority's (WMATA) board of directors voted to suspend all issue ads until the end of this year while it examines its own policy. The agency did not say the move was made in response to a particular ad. 

However, the head of the group behind the Muhammad ad, the American Freedom Defense Initiative's Pamela Geller, confirmed to the Associated Press Thursday that she had submitted the cartoon, which depicts Muhammad raising a sword and saying "you can't draw me," for consideration about two weeks ago. 

Muslims generally believe any physical depiction of Muhammad is blasphemous. The cartoon, by artist Bosch Fawstin, was the winner of the group's Muhammad cartoon contest in Garland, Texas, earlier this month. Two would-be terrorists ambushed security officers outside the event and were killed by local police. 

Geller said she submitted the cartoon with the caption "support free speech." She said her group is exploring its legal options and looking at other cities to potentially run the ads.

"Look, this is an end run around the First Amendment," she said in a telephone interview after the board's ruling. She called transit officials "cowards" for not being willing to run the ads and said "rewarding terror with submission is defeat."

This is not the first time an American Freedom Defense Initiative ad has sparked controversy. In 2012 the group took transit agencies in New York and Washington to court to force them to display a different provocative ad which read: "In any war between the civilized man and the savage, support the civilized man. Support Israel. Defeat Jihad."

WMATA said in a statement Thursday that officials will be reviewing the agency's ad policy.

"In the coming months, Metro will fully consider the impact that issue-related advertisements have on the community by gathering input from riders, local community groups and advocates. Metro will also carefully examine the legal concerns related to displaying, or discontinuing the display of, issue-related advertisements. Following this internal review and outreach period, the Board of Directors will make a decision about how to move forward with its advertising policy," the agency said in a statement.

Issue ads bring in approximately $2 million dollars annually, so suspending those kinds of ads for the remainder of the year could cost the agency approximately $1 million, spokesman Dan Stessel said. Advertising throughout the bus and train system, including both issue ads and commercial advertisements, brings in approximately $11 million, Stessel said.

The Associated Press contributed to this report.