SACRAMENTO ? As many as 5,000 California convicts will be transferred out of state to ease an overcrowding crisis in the nation’s largest prison system, a top corrections official said Friday.

“We are severely overcrowded, and the need for more space is absolutely critical,” state Corrections Secretary James Tilton said in a statement. “This decision is being made to protect public safety.”

In December, a federal judge warned that he would start releasing inmates early or prohibit convicts from being sent to state prisons from county jails unless the state acted immediately to ease overcrowding.

The threat followed an executive order signed by Gov. Arnold Schwarzenegger in October authorizing voluntary and involuntary transfers of up to 5,000 inmates. At the time, a survey found that nearly 20,000 inmates were willing to be sent voluntarily to other states.

Since then, however, only about 380 inmates have volunteered, despite a marketing campaign by the Department of Corrections and Rehabilitation that included videos showing inmates in better conditions in out-of-state prisons.

In one video, a former California inmate boasts about having television selections that include ESPN.

In this undated photo released by the California Department of Corrections, inmates sit in crowded conditions at California State Prison in Los Angeles. California's prison secretary on Friday said the state will force the transfer of up to 5,000 inmates to other states to help control the crowded prisons.

California’s 33 state prisons are designed to hold 100,000 inmates but currently house about 174,000. About 16,000 inmates sleep in gymnasiums, hallways and other common areas filled with beds.

“We will continue to seek volunteer inmates who are willing to serve their sentences in other states,” Tilton said. “But we also will begin to move inmates involuntarily so that they are no longer sleeping in gymnasiums, day rooms and other inappropriate areas of the prisons.”

The first transfers could start within days, although administrative appeals by inmates could delay some for up to 10 weeks.

Private prisons in Mississippi, Arizona and Oklahoma are likely to receive transfers.