THE HAGUE, Netherlands (AP) _ Two Muslim officers went on trial Tuesday for war crimes during the Bosnian war, the highest-ranked Muslims to face justice for atrocities in a conflict often seen as fomented by Serbs.

Retired Gen. Enver Hadzihasanovic, 53, commanded the 3rd Corps of the Muslim army in central Bosnia during the 1992-95 conflict. Amir Kubura, 39, was a brigade commander under Hadzihasanovic.

Prosecutors at the U.N. tribunal in The Hague have charged the men with murdering civilians and prisoners of war; horrific mistreatment of prisoners; and plundering and destroying villages in central Bosnia. If convicted, they face up to life in prison.

The men have pleaded innocent, and their lawyers declined to make opening statements.

``This is a case about command responsibility, about the criminal responsibility of the two accused for failing to prevent and punish war crimes by their subordinates,'' U.N. prosecutor Ekkehard Withopf said in his opening arguments.

``It demonstrates that all sides to the conflict _ though in different areas and on different scales _ committed violations in humanitarian law.''

The war in Bosnia, like the earlier war in Croatia, began after the country declared independence from Yugoslavia and its Serb minority rebelled. Bosnian Serbs fought with the backing of the Serb-dominated federal Yugoslav army, hoping to remain part of a larger Serb-dominated Yugoslavia or Serbian state.

The tribunal was set up to prosecute high-ranking war crimes suspects on all sides during the breakup of Yugoslavia in the 1990s, though in practice the suspects have been mostly ethnic Serbs and a few Croats. Hadzihasanovic and Kubura are the highest-ranking Muslims to face trial, though other top Muslim officers and politicians have been indicted and lower-ranking officers convicted.

Most victims of their alleged crimes were ethnic Croats captured after fighting erupted between Bosnian Muslims and Croats in March 1993 over the 30 percent of Bosnia not then under Serb control.

However, Withopf described an incident on Oct. 20, 1993, when Serb prisoner Dragan Popovic was beheaded by foreign Muslim ``mujahedeen'' troops who allegedly answered to Hadzihasanovic. Other prisoners allegedly were then forced to kiss the severed head before the body was buried.

The prosecutor also told of a makeshift prison in a former music school in the town of Zenica where Muslim guards allegedly took Croat prisoners outside for nightly ``singing lessons.''

Instead, they were beaten with ``rifle butts, metal hooks, wooden sticks and handles, batons, truncheons, knuckle-dusters, wooden staves, boots and telephone cables,'' Withopf said. Other prisoners were forced to beat themselves and each other, he said.

He also described a June 8, 1993, massacre involving Muslim soldiers who marched a group of captured Croat soldiers and civilians from the city of Maline to another location. When a prisoner started screaming, the soldiers _ who answered to the two suspects _ shot at the group at close range, killing at least 24 people, Withopf said.

He said survivors would testify at the trial, which is scheduled to run through July.

He said both accused men were ``well aware'' of these and other incidents, and that they also knew of international codes of law requiring them to prevent their troops from committing war crimes and to punish them when they did.

In 1998, the Muslim deputy commander of a prison camp, Hazim Delic, and a guard, Esad Lanzo, were sentenced to eight and 15 years, respectively, for raping, beating and murdering Serb prisoners.