The Supreme Court on Friday turned down California's request to delay a federal court order related to state prison overcrowding.

The justices refused to extend a deadline beyond Sept. 18 for telling a special three-judge panel how California will reduce its inmate population by 40,000, roughly a quarter, over two years.

The judges called for the reduction so the state can improve medical and mental health care for inmates in its 33 adult prisons. The federal courts have found the care so poor that it violates inmates' constitutional rights.

While rejecting the state's plea for a delay, the court noted that the three-judge panel has agreed not to put a final order into effect until after the justices have had a chance to review its decree.

The special three-judge panel had rejected California's request for a delay earlier this month, sending the matter to the high court.

In addition to its failed request for a delay, the Schwarzenegger administration is appealing to the Supreme Court the panel's inmate-release order. It has been joined by Republican legislators and associations representing prosecutors, sheriffs, police chiefs and chief probation officers.

The administration argues that the federal courts are overreaching in their effort to direct the state's affairs and are violating a federal law that restricts judges' actions in inmates rights cases