Along with a Croat, the three Muslims were accused of murder, torture and rape of Bosnian Serb inmates at the Celebici camp in central Bosnia in 1992.
The case offers the United Nations war crimes tribunal in The Hague a chance to demonstrate its impartiality, in the face of charges from Serbia and the Bosnian Serbs that it has an anti-Serbian bias. Most of the 74 men so far indicted by the tribunal are Serbs, including Radovan Karadzic and Ratko Mladic, the wartime Bosnian Serb leaders.
The Celebici case breaks new ground for the UN tribunal, since it marks the first time that any government in former Yugoslavia has voluntarily handed over war-crimes suspects to face trial. Hazim Delic and Esad Landzo were arrested last May in Bosnia, from where the Muslim-led authorities transferred them to The Hague.
Prosecutors allege at least 14 Serbs died terrible deaths at Celebici and that many more suffered torture. Delic, 32, the camp's Muslim deputy commander, and Landzo, a 23-year-old Muslim guard, are accused of beating men to death with steel cables, shovels, baseball bats and wooden planks and of torturing them with acid, electric shocks and pliers.
According to the indictment, Serb women were raped at Celebici, and prisoners were forced to imitate animals and perform oral sex on each other. One man is said to have died after a Muslim political party badge was nailed into his head.
Zejnil Delalic, 48, the Muslim military officer in charge of the region, and Zdravko Mucic, 41, the Croatian chief of the camp, are accused of overall responsibility for the atrocities.
They are the highest-ranking defendants so far to stand trial for alleged war crimes in former Yugoslavia. Like their two fellow-defendants, they maintain their innocence.
The International Red Cross first reported the Celebici camp as a place of harassment and torture in August 1992, the same month that world opinion was shocked by the television news pictures of emaciated Muslim prisoners at Bosnian Serb camps.
The Bosnian Serbs' behaviour received much closer scrutiny in 1992 than did that of their Muslim and Croat enemies, possibly because the tide of war was running strongly in the Serbs' favour at that time.