WASHINGTON (AP) — The Supreme Court delayed a ruling in Terry Nichols' request for a new trial in the Oklahoma City bombing case, saying the government must first respond to his assertion that mishandled evidence in Timothy McVeigh's case adversely affected him.

The court's decision Monday to order a response from the Justice Department raised the possibility that the justices would reopen the case involving Nichols, convicted as a conspirator in the April 1995 bombing of the Alfred P. Murrah Federal Building.

This came in the wake of the disclosure that the FBI failed to provide McVeigh's attorneys with thousands of documents at the time of McVeigh's trial in 1997.

Lawyers for McVeigh last week asked a federal court in Denver to stay his scheduled June 11 execution for the bombing at a federal prison facility in Terre Haute, Ind.

The court's brief order on Monday asked the Justice Department to respond to Nichols' assertion that the mishandled material might have affected Nichols' trial.

But that order did not address allegations by Nichols' lawyer that the FBI may have deliberately withheld information both from the bombing defendants and from federal prosecutors.

Nichols was sentenced in 1997 to life in prison after he was found guilty of involuntary manslaughter and conspiracy for his role in the 1995 bombing that killed 168 people. He was acquitted on federal charges of first- and second-degree murder.

Nichols has long contended that his lawyers did not have access to all the investigative material due them before trial. That allegation was the basis of an unsuccessful appeal to the Supreme Court earlier this spring, before the revelation that the FBI had failed to turn over more than 4,400 documents to lawyers for Nichols and McVeigh.

Nichols' lawyer, Michael Tigar, tried to revive the appeal after the FBI admitted the blunder.

"We believe that the entire issue of (evidence) production should be subjected to the test of adversary review," Tigar wrote in a court filing last month.

Nichols wanted a hearing or investigation by a lower court, which could order a new trial if it found serious errors by federal authorities.

The court asked for a response from the solicitor general's office within 30 days. That likely means the issue will not be decided before the court takes its summer break.

The court routinely denies nearly every request for a second chance made by losing parties. It is quite unusual for the court to ask for a response to such a request but is still far from an indication that the court will grant Nichols' appeal.

The court denies the overwhelming majority of rehearing petitions, even after requesting a response.

Nichols' lawyer has indicated that some of the mishandled material apparently concerns the FBI's search for John Doe No. 2, a possible suspect in the bombing. The FBI later concluded that John Doe No. 2 did not exist, but the possibility of another suspect was a central issue in Nichols' trial.

The FBI admitted the document mistake just days before McVeigh was scheduled to die for his role as mastermind of the deadly bombing.

Attorney General John Ashcroft delayed McVeigh's execution until June 11 to give defense lawyers time to look over the new material but said nothing in it would undermine McVeigh's conviction or death sentence.

McVeigh has since asked for another postponement, and he could ultimately follow Nichols' lead and seek a new trial or sentencing hearing.

Ashcroft said he will fight any attempt to delay the execution beyond June 11.

McVeigh lawyer Richard Burr cited Nichols' case in announcing McVeigh's decision to fight the June 11 date. The Nichols jury rejected a death sentence in part because jurors believed other people may have been involved in the crime, Burr said.

"That is a starting point for where we are right now in court," he said.

The case is Nichols v. United States, 00-8900.