Defense lawyers for Radovan Karadzic called on the Yugoslav war crimes tribunal Monday to drop all charges against the former Bosnian Serb leader because of an alleged immunity deal with U.S. peace envoy Richard Holbrooke.

In a motion, the lawyers say Holbrooke promised in July 1996 that Karadzic would not be prosecuted at the U.N. court in The Hague if he relinquished power and dropped out of public life. They cited two senior Bosnian Serb officials present at a meeting where the deal allegedly was brokered as saying that Holbrooke promised the tribunal would "disappear."

Karadzic's lawyers concede that Holbrooke never signed any written version of the deal, but have called for a special hearing to establish whether the deal was made and whether it is binding on the court.

"At the time the agreement was entered into, I had no doubt that Richard Holbrooke had promised that I would not be prosecuted at the ICTY and that he had the authority to make that promise," Karadzic says in a written statement dated April 22 that was attached to the motion.

Rumors about the exact terms of the deal that pushed Karadzic off the Bosnian political stage he had dominated throughout the bloody 1992-95 war have persisted since he left office in 1996.

Holbrooke, who is now the U.S. government's special envoy for Pakistan and Afghanistan, has repeatedly denied promising Karadzic immunity from prosecution. Prosecutors did not immediately return calls seeking comment.

The motion is Karadzic's latest attempt to avoid trial at the U.N. court on 11 charges including genocide for allegedly masterminding Bosnian Serb atrocities during the 1992-95 Bosnian war.

"No matter how innocent you are, you never want to face a trial because you never know what the outcome will be," said Karadzic's American legal adviser Peter Robinson.

After more than 12 years on the run from justice, Karadzic was arrested on a Belgrade bus last July posing as "Dragan Dabic," a bearded new age guru.

Dealing with past motions linked to the so-called Holbrooke agreement, tribunal judges have said they would not be bound by it even if it is proved to exist.

But lawyers for Karadzic dispute that, claiming Holbrooke was acting on behalf of the United Nations when he made the deal and that the tribunal is a United Nations court.

"They didn't have all of the facts before them in terms of the Security Council and the apparent authority it gave to Richard Holbrooke," Robinson said. "We're hoping that when (the court) has all the facts ... that it will see things differently."

The alleged deal was made during negotiations in Belgrade on July 18 and 19, 1996, at which Karadzic was not present. Instead, Holbrooke negotiated with other senior Bosnian Serbs and Karadzic's political mentor, Serb President Slobodan Milosevic.

In their motion, Karadzic lawyers cite a declassified cable dated July 22, 1996, from the then-U.S. Ambassador to Bosnia John Menzies to the State Department in which Menzies reports that two senior Bosnian Serbs who attended the meeting told him that Holbrooke had led them to believe the tribunal would "disappear" after Bosnian elections that were scheduled for September 1996.

That cable and an agreement signed by Karadzic that makes no mention of concessions in return for letting go the reins of power are among several documents attached to the motion.

But there is no agreement signed by Holbrooke and Robinson concedes there likely never was.

"Holbrooke declined to put any of his promises in writing, so we don't expect ever to find any written agreement signed by Holbrooke," Robinson told reporters at a press conference in front of the high fence surrounding the tribunal.