Updated

A conservative advocacy group on Friday called on the Justice Department to investigate a weekly prayer session on Capitol Hill that Muslims with terrorist ties have been participating in since the Sept. 11 terrorist attacks.

The American Center for Law and Justice, founded by the Rev. Pat Robertson, issued the demand one day after FoxNews.com revealed that notorious Al Qaeda cleric Anwar al-Awlaki was among the controversial figures who has attended the weekly Friday Jummah prayers hosted by the Congressional Muslims Staff Association during the Clinton, Bush and Obama administrations.

The group held prayers informally for about eight years before gaining official status in 2006 under the sponsorship of Rep. Keith Ellison, D-Minn., one of two Muslims currently serving in Congress.

"It is unbelievable that the very terrorists who want to destroy America are permitted to meet in a congressionally sanctioned setting on Capitol Hill," said Jay Sekulow, chief counsel of American Center for Law and Justice. "This raises a host of significant questions – including concerns about national security.

"We're demanding that the Department of Justice conduct an investigation and take immediate action to halt what appears to be a pattern of inviting Islamic extremists with ties to terrorism to participate in these events," he continued.

More On This...

The Justice Department declined to comment.

There appears to be no public record of the people the Congressional Muslims Staff Association has invited to Capitol Hill, but FoxNews.com was able to glean a portrait of the Jummah prayer meetings through video footage, news reports, court records and social media posts. Among those who have participated are an Al Qaeda leader, the head of a designated terror organization and a confessed jihadist-in-training

Sources told FoxNews.com that Congressional Muslims Staff Association is comprised mostly of young Hill staffers who, for the most part, do not play a role in bringing in speakers; they say organizations like the Council on American-Islamic Relations have a heavy hand in selecting and bringing in outside guests.