The Defense Department is looking into how access was granted a year ago to an evangelical Christian group that shot a promotional video inside the Pentagon. It included active duty military officers speaking on the group's behalf while in uniform.

A Pentagon spokesman said Monday the Defense Department had received a letter from a religious freedom watchdog group raising questions about whether the access granted to the Christian Embassy violated the Constitution or regulations prohibiting military endorsement of any one religion or religious organization.

Christian Embassy Executive Director Robert Varney said his organization was granted permission by the Defense Department to come in and tape service men and women expressing support for the group, but that a note is being added to the video to clarify that the speakers' words do not represent the military or any government agency.

"We don't think we did anything in violation," Varney said. "The Pentagon gave us permission to film the video, and I don't think they'd give us permission if it were in violation of the regulations."

The organization was established 31 years ago to promote prayer groups and Christian values among government officials.

Service regulations in general prohibit active-duty officers from lobbying for political causes while on duty or wearing their uniforms. The issue of religion in the military is trickier, with regulations seeking to both uphold religious freedom and protect members from proselytizing.

In letters released Monday, the Military Religious Freedom Foundation asked that the Defense Department's inspector general investigate the matter and release any documents authorizing the officers' involvement in the film.

Mikey Weinstein, founder of the foundation, said in a statement he hoped the footage would serve as "a testament to systemic problems of religious bias and constitutional neglect that continue to occur within the United States armed forces."

Maj. Stewart Upton confirmed that acting Inspector General Thomas F. Gimble had received a letter from Ezra W. Reese, and it will now be up to the Defense Department inspector general to decide whether the issue warrants a formal investigation.

Upton emphasized several points about Defense Department policy, including that it does not endorse any one religion or religious organization; it provides free access of religion for all members of the military services; it does not judge the validity of any one religious expression over the validity of any other and it supports free access for service personnel to the religious expression of their choosing.

According to a 1988 directive, department policy states "requests for accommodation of religious practices should be approved by commanders when accommodation will not have an adverse impact on military readiness, unit cohesion, standards or discipline."

Featured in the video are four generals and three colonels, including Maj. Gen. Jack Catton Jr., who is on active duty at Langley Air Force Base in Virginia. Catton was investigated by the Air Force last spring after he sent an e-mail from his work account urging Air Force Academy graduates to contribute to a Republican candidate for Congress.

Catton's spokeswoman said that investigation resulted in administrative actions that have not been made public. Catton declined to comment about the video.

In the video, Catton said the Christian Embassy helped inspire Christian faith throughout the Pentagon: "I think it's a huge impact because you have many men and women who are seeking God's counsel and wisdom as we advise the chairman (of the Joint Chiefs of Staff) and the secretary of defense. Hallelujah."

The Christian Embassy was founded by Bill Bright, who also founded Campus Crusade for Christ International. The group hosts a prayer breakfast each Wednesday in the Pentagon's executive dining room, featuring speakers on "how to integrate faith, personal beliefs and work."

The group also sponsors weekly meetings throughout the Pentagon in which "staffers share and sharpen one another in their quest to bridge the gap between faith and work," according to the group's Web site.

Upton said as a matter of policy the inspector general's office does not confirm the existence of ongoing investigations.

FOX News' Mike Emanuel and Nick Simeone and The Associated Press contributed to this report.