A civil rights group sued the state of California and its prison system Thursday, saying the long-term confinement of inmates in a special high-security unit at Pelican Bay State Prison amounted to torture and human rights violations, according to an article from Reuters.

The lawsuit demands reforms and seeks class-action status for more than 500 current prisoners who have been held in the Special Housing Unit at the super-maximum-security prison for between 10 and 28 years, the article says.

"The prolonged conditions of brutal confinement and isolation such as those at Pelican Bay have rightly been condemned as torture by the international community," Jules Lobel, president of the Center for Constitutional Rights, said in announcing the suit, filed in U.S. District Court in Oakland.

The Special Housing Unit is a virtual prison within a prison and held about 1,100 prisoners last year, according to Reuters. Inmates spend at least 22-1/2 hours a day in small, windowless concrete and steel cells with no telephone privileges and very limited contact with other inmates or guards, according to the lawsuit.

"To keep people in these crushing conditions is beyond the pale of any civilized nation," Lobel said, and violated the U.S. Constitution.

The lawsuit asks for the release of prisoners who have spent more than a decade in the Special Housing Unit and alleviation of "conditions of isolation, sensory deprivation, lack of social and physical human contact" among other things, the article says.

The plaintiffs are also seeking a review of all prisoners in the unit and the need to confine them there.

California Department of Corrections and Rehabilitation spokesman Jeffrey Callison disputed the accusations and said prisoners, some of whom are considered risks to others in prison, were sent to the unit for legitimate security reasons, according to Reuters.

Most inmates held in Pelican Bay's high-security unit are there because of gang affiliations, he said, and could be returned to the prison's general population by disavowing those ties, the article says.

While some inmates can earn their way out of the high-security unit at Pelican Bay by renouncing gang ties, Lobel said, doing so puts them and family members at risk of retaliation, making it an unacceptable choice, according to Reuters.

Lobel said the high-security unit at Pelican Bay also was unique when compared to other states in that inmates have such limited human contact, including being denied telephone calls, causing profound mental harm, Reuters reports.