A former Bosnian Muslim commander who led the defence of Srebrenica against Bosnian Serbs has been dubbed a "warlord" in his trial at The Hague.
Oric is accused of murder and mistreatment of Serbs
Naser Oric, 37, is the first Muslim to be charged with war crimes committed in the Srebrenica area.
Prosecutors say he is guilty of murdering and torturing Serbs before the 1995 massacre of Muslims.
Mr Oric, who denies the charges, is seen as a hero by many Bosnian Muslims who survived Srebrenica.
"This is the case of a young commander who became a warlord," prosecutor Jan Wubben said in his opening statement.
"In accepting his role as commander, he amassed authority and power. War crimes of murder, wanton destruction and plunder were committed under his command."
He said Mr Oric commanded troops that destroyed 50 Serb villages around the town between 1992 and 1993, causing thousands of Bosnian Serbs to flee.
Mr Oric's lawyers say the attacks on Serb villages were legitimate actions against military and strategic targets, or operations to obtain food for the starving population of Srebrenica.
Defence lawyer John Jones said the Bosnian Serb troops had "a genocidal intent" from the start of the siege in 1992 aimed at a slow death for the people of Srebrenica by shelling, sniping, starvation and disease.
He said Mr Oric had fought bravely to defend a besieged enclave.
"He and his men fought like lions," he said. "Oric was an outstanding warrior, leading by example. The evidence will simply not bare out the charges."
Mr Jones also warned the judges against putting Muslims on same level as Serbs.
The arrest and transfer of Mr Oric last year sparked controversy among Bosnian Muslim survivors of the massacre, says the BBC's Geraldine Coughlan in The Hague.
Some were outraged because they consider Mr Oric a hero, while others say he is a criminal and profiteer who made a fortune on the black market in Srebrenica, our correspondent says.
She adds that the trial is important in the tribunal's efforts to show even-handedness in prosecuting war crimes in the Balkans.
Mr Oric, an ex-bodyguard of the former Yugoslav President Slobodan Milosevic, is charged with seven murders, and the cruel treatment of prisoners committed by men under his command.
The indictment says they beat Serb detainees and used pliers to pull out their teeth.
Some are said to have been beaten until they lost consciousness or even died. Others were reportedly humiliated in ways such as being forced to drink urine.