The largest Indian legal rights group in the nation joined in the Utah State Prison sweat lodge case Thursday, writing that state officials are forwarding "penological myths" to deny Indian inmates religious freedom.

The Native American Rights Fund filed a friend-of-the-court brief in U.S. District Court for Utah Thursday on behalf of several Native American prison inmates suing the state for the right to practice religion in a sweat lodge.The state has refused to permit use of the sweat lodges, in part because they could present security risks. Prison officials have, however, offered the use of a transparent sweat lodge, which an inmate attorney found unacceptable.

The fund said state Corrections Department Director Gary DeLand's concerns that use of sweat lodges - willow pole and blanket structures heated with hot rocks - present security risks is another "penological myth."

"It is important to note here that few of the `penological myths' commonly utilized by prison officials ever become reality," the fund wrote in the brief.

For example, the fund cited one case in which a state prison restricted inmates from wearing long hair for religious purpose because it presented a security risk. The court found the prisons position "without substance."

"There are scores of cases in which the allegations of security threats . . . when examined in the crucible of litigation, have proved to have little more than a mere possibility of occurrence," the fund said.

The fund concluded that by restricting religious practices in sweat lodges the prison has reduced religious "rights" to religious "prisons." "This . . . runs contrary to well-established first amendment jurisprudence and must be rejected."