(Adds background, ACLU comment, paragraphs 11-12)
Feb 22 (Reuters) - More than 300 inmates from a Texas federal prison damaged in an uprising were relocated on Sunday and hundreds more were to be moved later in the day, according to the private contractor that operates the prison.
The inmates at the Willacy County Correctional Center in Raymondville, Texas, were being transferred to other U.S. Bureau of Prisons facilities in a process that will continue next week, said Issa Arnita, spokesman for Management and Training Corp.
"Inmates continue to be fully cooperative with the relocation efforts," Arnita said in a statement.
Damages to the prison will be assessed when the inmates are gone so that repairs can begin, Arnita said. "Initial assessments indicate significant damage to the plumbing and heating and cooling systems," he said.
The prison about 40 miles (64 km) from the Mexican border primarily holds people who have entered the United States illegally. The privately operated prison is among several known as Criminal Alien Requirement (CAR) facilities.
The unrest began on Friday when prisoners refused to come to breakfast or report for work to protest problems with medical services at the facility, the San Antonio Express-News newspaper and local broadcaster KGBT-TV reported.
The inmates broke out of their housing structures and converged in the recreation yard, setting fire to several Kevlar domes, or tents, that serve as prison housing, the newspaper said.
The situation was largely under control by Saturday but as many as 2,800 inmates will have to be moved, the U.S. Bureau of Prisons said in statement published by KGBT.
In a statement, the American Civil Liberties Union of Texas said its 2014 report on five CAR prisons in the state showed their conditions fell well Bureau of Prisons standards
"Though not surprised, we are saddened by the events in Raymondville and hope they can be a catalyst for the changes we have demanded in our report," the ACLU said.
A Bureau of Prisons spokesman did not immediately return a call for comment. (Reporting by Kevin Murphy in Kansas City; Editing by David Evans and Tom Brown)