Mladic 'was treated for cancer in Belgrade' (AFP)

THE HAGUE (AFP) – Wartime Bosnian Serb army chief Ratko Mladic was treated for cancer two years ago while evading genocide charges, his lawyer said Thursday on the eve of the ex-general's first appearance at a UN court.

"I have medical records showing that he was treated for lymphoma in 2009 in a Belgrade hospital," Belgrade-based lawyer Milos Saljic who has previously said his client won't live to see trial, told AFP.

The prosecution of the International Criminal Tribunal for the former Yugoslavia (ICTY), meanwhile, said the trial of the man dubbed the "Butcher of Bosnia" would not start for months.

"It is a complex case, it will take time to prepare," spokesman Frederick Swinnen said.

"It will take several months before the trial starts." The trial itself is expected to last several years.

Mladic's one-time mentor, Serbian President Slobodan Milosevic, died in The Hague four years into his own genocide trial in 2006, of a heart attack.

On Friday, 69-year-old Mladic will be asked to plead to 11 counts of genocide, war crimes and crimes against humanity at the UN-backed court in The Hague.

For long Europe's most wanted man for atrocities committed during Bosnia's 1992-95 war that killed 100,000 people, Mladic was arrested in northeast Serbia last Thursday and flown to The Netherlands on Tuesday after Serbian judges denied his appeal on health grounds and found him fit to stand trial.

Belgrade daily Press quoted Saljic as saying that Mladic had suffered three strokes and two heart attacks.

At his first court appearance on Friday, Mladic will be asked by a judge to identify himself and to answer questions about his health and conditions of detention.

He may then have the 62-page indictment read out, after which he will be asked to plead to the charges. He will have 30 days to do so, failing which the court will enter a not-guilty plea on his behalf.

Mladic is accused of masterminding the 1995 Srebrenica massacre of about 8,000 Muslim men and boys, and the 44-month siege of the capital Sarajevo from May 1992 in which 10,000 people died.

If Mladic does enter a guilty plea, there will be no trial and a date will be set for a sentencing hearing. Fe faces a maximum sentence of life in prison.

International news crews swarmed into The Hague Thursday and satellite TV trucks jostled for space outside the tribunal.

The tribunal had to rent extra space at a conference centre across the road to handle the expected overflow of visitors hoping to catch a glimpse of the ex-general in the dock.

Large screens will be erected and extra chairs put out for people to follow the hearing, with the 100-odd seats in the courtroom and even the ICTY lobby expected to be overrun, according to the court's press office.

The ICTY also announced it has assigned a Serbian lawyer from a list of accredited counsel to represent Mladic at his first appearance.

Mladic has been informed of his right to appoint a permanent lawyer or to have one assigned to him by the court if he cannot pay, said a court document.

But it was not clear whether he has retained counsel or would opt instead to conduct his own defence, as his former political head Radovan Karadzic has been doing since his own trial on similar charges opened in October 2009.

Swinnen said Thursday it was "possible but not probable" that the trials of the two men regarded as the political and military architects of the Bosnian campaign will be joined, pointing to practical difficulties arising from the fact that Karadzic's case has been running for 18 months.

Mladic's family are not expected among the throngs at court Friday.

"The family will not go to The Hague in the next 15 days," Saljic has told AFP, adding they would wait for the initial appearance to pass and then visit him "calmly" in The Hague.

Five representatives of victims' groups said Thursday they were on their way to The Hague to attend the hearing.

But a lawyer for Alma Mustafic, who lost her father Rizo in the Srebrenica massacre, said she was not ready to face Mladic and would stay home.

"Her father's remains have just been discovered in a mass grave and he will be reburied on July 11 in Srebrenica. She is not yet up to meeting her father's murderer," lawyer Liesbeth Zegveld told AFP.