(CNN) -- Former Bosnian Serb president Radovan Karadzic, accused of masterminding "ethnic cleansing" deportations and killings of Bosnian Muslims and Croats, has been arrested after more than a decade in hiding, a U.N. war crimes tribunal said Monday.

Radovan Karadzic, shown here in 1995, is charged with war crimes relating to the 1992-1995 Bosnia conflict.

Karadzic, 63, is charged with genocide, crimes against humanity and violations of the law of war.

Last seen in public in 1996, Karadzic was the Bosnian Serb political leader during the 1992-1995 war that followed Bosnia-Herzegovina's secession from Yugoslavia.

The conflict included the Srebrenica massacre of thousands of Bosnian Muslims and a deadly, 44-month siege of Sarajevo.

Former U.S. diplomat Richard Holbrooke blamed Karadzic for all the deaths in the three-year war in Bosnia, which had the bloodiest of the Balkan conflicts that accompanied the breakup of Yugoslavia.

"Without Radovan Karadzic, this thing wouldn't have happened," Holbrooke told CNN. Watch CNN's Christiane Amanpour explain Karadzic's rise and fall »

Early estimates of the death toll from the three-year war ranged up to 300,000, but recent research concluded about 100,000 were killed.

Vladimir Petrovic, the charge d'affairs at the Serbian Embassy in Washington, said his government's security forces made the arrest, but said no further details had been released.

"I think this is an example that the Serbian government is committed to all its international obligations and that it will continue cooperation with the International Tribunal for the former Yugoslavia," Petrovic said.

Serge Brammertz, the chief prosecutor of the International Criminal Tribunal for the former Yugoslavia, congratulated Serbian authorities for taking Karadzic into custody and called it "an important day for the victims."

"It is also an important day for international justice, because it clearly demonstrates that nobody is beyond the reach of the law and that sooner or later all fugitives will be brought to justice," Brammertz said.

He said authorities "in due course" will determine when Karadzic is to be transferred to the tribunal at The Hague.

Karadzic's arrest leaves former Gen. Ratko Mladic, the Bosnian Serb military commander, as the top-ranking war crimes suspect still at large.

"While this is an important milestone, the work of the International Tribunal will not be complete until all fugitives have been arrested and tried," a spokesman for U.N. Secretary-General Ban Ki-Moon said.

News of Karadzic's arrest was greeted with jubilation in the streets of Sarajevo, the Bosnian capital, which Bosnian Serb forces had shelled heavily during the war.

"Today, I can tell you that I feel kind of good," said Zlatko Lagumdzija, a former Bosnian prime minister wounded during the siege. He said the arrest could offer "a chance for new thinking" in Bosnia, still grappling with the scars of war.

"Today it looks like a new wind is moving from Belgrade," he said. "And I hope it will be a signal to Bosnian authorities that the state has to be set in order to deliver what the state is supposed to deliver: peace and justice."

Karadzic, a one-time psychiatrist and self-styled poet, declared himself president of a Bosnian Serb republic when Bosnia-Herzegovina seceded from Yugoslavia in 1992.

The Bosnian Serbs, backed by the Serb-dominated Yugoslav military and paramilitary forces, quickly seized control of most of the country and laid siege to Sarajevo, the capital.

During the conflict that followed, the Serb forces launched what they called the "ethnic cleansing" of the territories under their control -- the forced displacement and killings of Muslims and Croats.

Among the crimes Karadzic is accused of overseeing is the massacre at Srebrenica, a U.N. "safe area" overrun by Serb troops in July 1995. Nearly 8,000 Bosnian Muslim men and boys were killed at Srebrenica, the worst European massacre since World War II.

During the siege of Sarajevo, "shelling and sniping killed and wounded thousands of civilians of both sexes and all ages, including children and the elderly," according to the U.N. tribunal's indictment of Karadzic.

He was removed from power in 1995, when the Dayton Accords that ended the Bosnian war barred anyone accused of war crimes from holding office.

But he remained "kind of a Robin Hood" to Serbs during more than a decade as a fugitive, said Holbrooke, one of the architects of the Dayton Accords.

Serbia's government has been under increasing pressure to arrest war crimes suspects such as Karadzic and Mladic -- who were believed to be in hiding in Serbia rather than Bosnia.

The European Union warned in December that any steps toward allowing Serbia into the organization would depend on its cooperation with the war crimes tribunal.

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