An appeals panel has rejected Radovan Karadzic's claim that he cannot be tried at the U.N.'s Yugoslav war crimes tribunal because he was promised immunity by an American envoy, according to a ruling released Tuesday.

The decision dismisses the former Bosnian Serb leader's last legal challenge to his trial on 11 charges including genocide for allegedly masterminding atrocities against Bosnia's Muslims and Croats during the country's 1992-95 war.

Karadzic's trial had been tentatively scheduled to begin Oct. 21, but Karadzic has appealed for more time to prepare his defense.

In response, judges announced late Tuesday that they would delay the trial until a week after the prosecution files a fresh indictment that streamlines the case by reducing the number of crime sites.

Prosecutors have an Oct. 19 deadline to file the new indictment, meaning the trial would start on Oct. 26 at the latest.

Even though the new indictment contains few substantial changes, giving Karadzic only two days to read it "risks rendering the trial unfair," judges wrote.

The appeals panel's ruling brings to an end months of litigation revolving around a deal Karadzic said he cut in 1996 with U.S. envoy Richard Holbrooke.

Karadzic claimed that he stepped down as Bosnian Serb president and retired from public life in return for a pledge from Holbrooke that he would not be prosecuted in The Hague.

But the tribunal's five-judge appeals panel agreed with a previous ruling that the alleged deal was irrelevant.

"Even if the alleged agreement were proved, it would not limit the jurisdiction of the tribunal, it would not otherwise be binding on the tribunal and it would not trigger the doctrine of abuse of process," the appeals judges wrote.

They added that Karadzic is free to present evidence about the alleged agreement at his trial as it could have an effect on sentencing if he is convicted.

Holbrooke, a veteran diplomat who now is the Obama administration's envoy to Pakistan and Afghanistan, has always denied making an immunity deal with Karadzic.

The former Bosnian Serb leader was arrested last year on a Belgrade bus after more than a decade on the run from international justice. He was posing as a New Age guru and disguised with long hair, a bush beard and glasses.

Karadzic has pleaded innocent to all charges against him. Prosecutors say he minded atrocities by Serb forces including the 1995 massacre of 8,000 Muslim men in Srebrenica and the campaign of shelling and sniping during the siege of Bosnia's capital, Sarajevo.

His trial is expected to last three years.