The Hague war crimes tribunal appointed a prominent Belgrade lawyer on Thursday to defend Ratko Mladic, the Bosnian Serb commander whose coming trial on genocide charges is now the UN court's biggest case.

Mladic, 69, remains in isolation at Scheveningen prison on the Dutch coast before his arraignment on Friday. Serbian media reports said he would defer entering a plea, and the court would reschedule a further hearing in 30 days.

"Mladic is still separated from other prisoners. He can be kept like that for up to seven days following his arrival," tribunal spokeswoman Nerma Jelacic said.

The general was arrested in a Serb village last week nearly 16 years after his indictment. Most of that time he managed to live discreetly but safely in Belgrade, relying on loyal supporters who consider him a hero of the 1992-95 Bosnia war.

He is now in detention in the same facility as his political alter-ego, the wartime Bosnian Serb president Radovan Karadzic, who was the tribunal's last big catch in 2008 and who has been on trial since October 2009.

Karadzic also began the legal process by deferring his plea to the tribunal judges for 30 days.

Lawyers for both suspects say they are destined to meet in the coming days to discuss the possibility that their cases could be joined, either at their own request or that of tribunal prosecutors.

Three years to go 
The International Tribunal for former Yugoslavia, set up in 1993, expects to wind up by 2014. It has been criticised for lengthy procedures and is likely to avoid any move that would complicate completion of its two biggest remaining cases.

The court said it had appointed Aleksandar Aleksic as Mladic's interim legal counsel. Aleksic has defended a prominent Serbian army general and is currently representing a Bosnian Serb police chief accused of war crimes.

Aleksic is best known in Belgrade for his recent successful defence of the popular singer Ceca, widow of a notorious Serbian warlord, who avoided prison on charges of embezzlement.

Chief prosecutor Serge Brammertz on Wednesday said Mladic had used his power to commit atrocities that tore a nation apart and destroyed communities, and must be held to account.

A career soldier, Mladic was branded "the butcher of the Balkans" in the late 1990s after his campaign in the Bosnia war to seize territory for Serbs following the break up of the Serb-dominated Yugoslav federation of six republics.

Serb nationalists believe Mladic simply defended the nation and did no worse than Croat or Bosnian Muslim army commanders.

Court registrar John Hocking has contradicted comments by Mladic's lawyer and son that he was disoriented and mentally unfit for extradition and trial.

Hocking said Tuesday's transfer of Mladic to the court's detention unit "was a very cooperative, very smooth procedure".

"He was extremely cooperative. He made no comment on the charges against him. He asked a lot about procedures," Hocking said. "He was really paying attention and listening to the information we provided. We had good communication."

Mladic is indicted along with Karadzic for the 43-month siege of the Bosnian capital Sarajevo, in which some 12,000 people were killed, and the four-day slaughter of 8,000 Muslim men and boys in Srebrenica during the 1992-95 Bosnian war - the worst massacre in Europe since World War II.

Brammertz said his capture had come "very late but not too late" for justice to be done.