THE HAGUE(AFP) - Former Bosnian Serb army commander Ratko Mladic went on trial Wednesday accused of carrying out a brutal campaign of ethnic cleansing and Europe's worst massacre since World War II.

"Ratko Mladic assumed the mantle of the criminal goal of ethnically cleansing Bosnia," prosecutor Dermot Groome told judges as the trial opened at the Yugoslav war crimes court in The Hague.

Mladic, 70, has been indicted on 11 counts of genocide, war crimes and crimes against humanity for his role in the Balkan country's brutal 1992-95 war that killed 100,000 people and left 2.2 million homeless.

"The prosecution will present evidence that will show without reasonable doubt the hand of Mr Mladic in each of these crimes," Groome added after Mladic, dressed in a dark grey suit and patterned tie, sarcastically applauded judges as they entered the courtroom.

Mladic pleaded not guilty to the charges at an earlier court hearing last June.

Outside the court, a group of 25 women belonging to the "Mothers of Srebrenica" organisation representing widows and victims of the Srebrenica massacre, held a demonstration.

"This is the biggest butcher of the Balkans and the world," Munira Subasic, 65, told AFP. She lost 22 relatives to Bosnian Serb military forces when the enclave of Srebrenica was overrun in July 1995.

Almost 8,000 Muslim men and boys were systematically murdered as Bosnian-Serb forces under General Mladic's command overran the town and Dutch UN peacekeepers helplessly looked on.

 Groome displayed population maps showing the ethnic distribution in Bosnia before and after the war, explaining how mixed or predominantly Muslim municipalities became exclusively Serbian after a campaign of ethnic cleansing he said was one of Mladic's "strategic objectives".

The prosecutor said the very first objective was to "separate the Serbs from the other two national communities" -- Bosnians and Croats.

"Thousands of families were forced from their land," Groome added, as he told the court how groups of non-Serbs were executed and others forced to jump from a bridge by soldiers under Mladic's command.

Judge Orie warned both Mladic and people sitting in the public gallery not to make eye contact during the trial, after one of them was heard to utter the word "vulture".

"Mr Mladic, try and focus your attention on what's happening inside the courtroom," the judge said.

Prosecutors also hold him responsible for the 44-month siege of Sarajevo where his forces waged a "terror campaign" of sniping and shelling that left an estimated 10,000 people, the vast majority of them civilians, dead.

"Sarajevo was a model of diversity, a cosmopolitan city," said Groome.

"They (Bosnian Serb leaders) sought to destroy it, to sever the city in half,  with the Serbs living in one part and the non-Serbs in another part."

It was in pursuit of a "Greater Serbia" that Mladic allegedly also ordered his troops to "cleanse" other Bosnian towns, driving out Croats, Muslims and other non-Serbs.

After the war, Mladic continued his military career but went into hiding in 2000 after the government of his ally in Serbia, Slobodan Milosevic, fell.

Indicted for war crimes, he was on the run until May 2011 when he was arrested at a relative's house in Lazarevo, northeastern Serbia and flown to a prison in The Hague a few days later.

Two days ahead of the trial, his lawyers filed a request for a six-month adjournment, saying they needed more time to prepare a defence.

The judge said Wednesday the court was still considering whether to

postpone the case, on the grounds that the prosecution made a "significant error" which could affect the course of the trial.

During a string of pre-trial hearings, the ageing former general complained of his poor health and asked Orie if he could wear his military uniform.

Defence lawyer Branko Lukic said Mladic suffered three strokes in 1996, 2008 and 2011 and was partly paralysed on his right side.

Mladic however appeared in better shape than at his first appearance when the former general told the court he was a "sick man".

Lukic told journalists on Wednesday that Mladic had had extensive medical and dental surgery since his capture.

"He lost a lot of teeth" during his years as a fugitive, Lukic said.

The trial was due to continue on Thursday, before resuming on May 29.

Mladic faces life imprisonment if found guilty.