The nation's largest private prison company has paid more than $8 million in back wages and benefits to current and former employees at its federal prison facility in California City.

The U.S. Department of Labor said Tuesday that Corrections Corp. of America paid the money to staff at the California City Correctional Center after an investigation found it wasn't paying the rates required of federal contractors.

A department official says in some cases employees were paid 40 percent less than required by pay rate regulations established for contractors. The company also wasn't making required contributions to retirement accounts and health and life insurance.

Many workers will receive more than $30,000.

Messages left with the Nashville, Tennessee-based company spokesmen weren't immediately returned.