A federal lawsuit claims guards at a Mississippi juvenile lockup have smuggled drugs to inmates, had sex with some of them and denied others medical treatment and basic educational services.

The Southern Poverty Law Center, the American Civil Liberties Union and Rob McDuff, a Jackson attorney, filed the complaint Tuesday in U.S. District Court in Jackson on behalf of 13 plaintiffs against the Walnut Grove Youth Correctional Facility. The Justice Department also is investigating.

"These young men live in barbaric conditions," said Sheila Bedi, the law center's deputy legal director. "I have done prisons conditions work for almost 10 years, this is the most violent, corrupt abusive prison I've come across."

The complaint claims that guards allowed inmate fights that resulted in stab wounds and severe beatings, including one that left one youth with permanent brain damage. It also says inmates were stripped naked and held in isolation for weeks at a time and that sick inmates were denied proper health care.

Sex acts between inmates and prison guards and nurses occurred in isolated, camera-free areas of the prison, including individual cells, medical unit examination rooms and restrooms, the lawsuit alleges.

It also claimed handcuffed youth were kicked and punched by guards, while others secured in their cells were sprayed with chemical restraints.

The lawsuit names as defendants the Walnut Grove Correctional Authority, which is overseen by the town of Walnut Grove; the GEO Group, Inc., which is paid to run the prison; Health Assurance, LLC; warden Walter Tripp; Mississippi Department of Corrections Commissioner Chris Epps and Mississippi Education Superintendent Tom Burnham.

The lawsuit seeks class action status.

GEO Group, based in Boca Raton, Fla., and agency officials declined to comment on the lawsuit Tuesday.

Michael McIntosh said his son, Michael Jr., was beaten so badly earlier this year he sustained brain damage from which he'll never recover. McIntosh, of Hazlehurst, was at the news conference announcing the lawsuit. He wouldn't disclose the crime that led to his 21-year-old son's incarceration.

"After my son was attacked, no one would tell me where he was or what happened for two weeks," said McIntosh.

When he visited his son in a hospital about a month after the attack, he said his son "was so severely beaten, he couldn't see me."

The Justice Department last month sent a letter to Gov. Haley Barbour, urging the state to cooperate with the investigation, which would determine whether there are systemic constitutional violations at Walnut Grove. House Juvenile Justice Committee Chairman Earle Banks, D-Jackson, provided the letter from Thomas E. Perez, an assistant attorney general.

The governor's office said it knew of the letter and was cooperating with the investigation.

The lockup, which opened in 2001, is located in Leake County, about 60 miles northeast of Jackson, and houses some 1,200 inmates ages 13-22. More than half are jailed for nonviolent offenses, the complaint states.

Courts often require youth sentenced to the facility to complete their education while incarcerated, but most youth are denied access to basic education, the complaint said.

Understaffing at the prison is one of the main problems, according to the lawsuit, which cited reports from the Joint Committee on Performance Evaluation and Expenditure Review and the MDOC Corrections Auditor that have also raised concerns about the issue.

Taxpayers pay the Walnut Grove Correctional Authority $14 million each year to operate the prison, according to the complaint. It alleges that in many parts of the prison only one guard is assigned to a zone, which could hold as many as 60 inmates.

"It has a strong financial incentive to imprison as many youth as possible on the cheap," Bedi said.

Bedi and Banks were joined at a news conference Tuesday in Jackson by about a dozen members of a recently formed group who say they are relatives of inmates at the facility.