WASHINGTON (Reuters) - Senior U.S. lawmakers on Sunday condemned the suspected distribution of nude photographs of female Marines to military personnel and veterans via a social media network that promotes sexual violence, and called on the Marine Corps to fully investigate.

The Marine Corps Times, an independent newspaper focusing on issues involving the service, published an internal Marine Corps communications document with talking points about the issue, describing the social media network as a closed Facebook group with about 30,000 members. The network solicited nude photos of female service members, some of whom had their name, rank and duty station listed, the newspaper reported.

A Marine Corps spokesman told the newspaper that military officials are uncertain how many military personnel could be involved.

The chairman of the U.S. House of Representatives Armed Services Committee, Republican Mac Thornberry of Texas, and the panel’s senior Democrat, Adam Smith of Washington state, separately called for a complete investigation.

“Degrading behavior of this kind is entirely unacceptable,” Thornberry said in a statement. “I expect the Marine Corps to investigate this matter fully with appropriate consequences for those who willingly participated.”

Smith also called for proper care to be provided to the victims, and said that, “This behavior by Marines and former Marines is degrading, dangerous, and completely unacceptable.”

Officials from the Marine Corps Naval Criminal Investigative Service were not immediately available for comment.

The site talked of misogynist behavior, the Marine Corps document said, and the photos were on a secure drive in cloud storage, which has been removed.

The document advised a response along the lines of: “The Marine Corps is deeply concerned about allegations regarding the derogatory online comments and sharing of salacious photographs in a closed website. This behavior destroys morale, erodes trust, and degrades the individual.”

According to an annual report that the Pentagon released in May 2016, the U.S. military received about 6,000 reports of sexual assault in 2015, similar to the number in 2014, but such crimes are still underreported.