The "Fifty Shades of Grey" series of erotic novels are requested more by "high-value" prisoners at the Guantanamo detention camp in Cuba than the Quran, a U.S. congressman said.

Representative Jim Moran of Virginia was among congressional delegates who toured Camp 7 last week, the top-security facility that holds more than a dozen "high-value" prisoners, including five men charged with plotting the September 11 attacks on the United States in 2001, Reuters reports

"Rather than the Quran, the book that is requested most by the [Camp 7 detainees] is 'Fifty Shades of Grey.' They've read the entire series," Moran said, according to The Huffington Post.

"I guess there's not much going on, these guys are going nowhere, so what the hell," Moran quipped.

Moran, who favors shutting down the detention camp on the Guantanamo Bay U.S. Naval Base, said he learned about the book's popularity amongst the prisoners while touring Camp 7. Guantanamo holds 166 men in total.

Though journalists are not allowed to visit Camp 7 of the detention camp, they are able to tour other prisons and the library.

During a visit to the library last week, Reuters saw an eclectic mix of books in numerous languages. They books ranged from religious texts to "The Hunger Games," according to a librarian who goes by the nickname Zorro, Reuters reports.

Guantanamo librarians have said in the past that they screen reading material for sexual content, even blacking out photos of scantily clad women in the advertisements in sports magazines.