A federal judicial panel has rejected California's plan for reducing the state's prison population because it failed to meet the terms of an earlier court order.

In August, the panel ordered California to reduce its inmate population by roughly 27 percent, or 40,000, over two years. The courts have found that prison overcrowding is the main cause of negligent medical and mental health care.

Gov. Arnold Schwarzenegger's administration subsequently submitted a plan calling for a reduction of 23,000 inmates.

On Wednesday, the judges gave the administration 21 days to submit a new plan. If it's inadequate, the court said it will develop its own.

In a statement, the administration said it objects to what it sees as an arbitrary inmate cap but will respond to the court on Nov. 12.