The ads read: "19,757 Deadly Islamic Attacks Since 9/11/01. It's Not Islamophobia, It's Islamorealism. This Ad Paid For By The American Freedom Defense Initiative."
The ads are on 10 RTD buses in the Denver area. They are paid for by the American Freedom Defense Initiative.
The group pays to advertise on public transit around the country raising awareness to what they say is the greatest threat to national security: Islamic extremism.
RTD says it has received around a dozen complaints about the ads, which they say is fairly normal for controversial ads.
RTD spokesperson Scott Reed says the transit system does not endorse or promote any advertisements on its buses.
"There was no way to reject this ad on a legal basis," he said. "While we do not follow what it says we did have to run the ad."
Pamela Geller is a spokesperson for the American Freedom Defense Initiative.
"It's not that I'm singling out a group," she said by phone. "There is a problem, jihad is a problem. You can put as much lipstick as you want on it, it's not going away. We're going to need to address it. By calling it 'workplace violence' or pretending that it was some YouTube video, you're emboldening the jihadists - not in any meaningful way addressing the problem."
RTD says the ads will be running for another week and a half.
(KUSA-TV © 2012 Multimedia Holdings Corporation)