Helena, MT -

A disability-rights group claims Montana State Prison is warehousing hundreds mentally ill inmates without adequate mental-health care.

Disability Rights Montana filed a lawsuit Monday in U.S. District Court. It accuses seven officials with the state corrections and health departments of cruel and unusual punishment and due process violations.

The group says inmates found "guilty but mentally ill" are transferred from the Montana State Hospital to prison to open up hospital bed space or to avoid treating prisoners disliked by hospital staff.

Once in the Deer Lodge prison, the group claims mentally ill inmates are locked in solitary confinement, their medication and treatment are discontinued or they are deprived of clothes, bedding, proper food and human contact.

Corrections spokeswoman Judy Beck says the department has not been served the lawsuit.