Bosnian Serb wartime leader and top war crimes suspect Radovan Karadzic has been arrested, the office of Serbian President Boris Tadic said on Monday.

"Radovan Karadzic was located and arrested tonight" by Serbian security officers, said a presidential statement.

"Karadzic was brought to the investigative judge of the War Crimes Court in Belgrade, in accordance with the law on cooperation with the International Criminal Tribunal for the former Yugoslavia (ICTY)," the statement said.

Karadzic and his former military commander Ratko Mladic had been on the run from the ICTY for 13 years after they were charged with war crimes committed during Bosnia's 1992-1995 war. Mladic is still at large.

Serge Brammertz, the chief prosecutor of the ICTY -- which charged Karadzic and Mladic with war crimes, genocide and crimes against humanity in 1995 -- welcomed the arrest.

"I was informed by our colleagues in Belgrade about the successful operation which resulted in the arrest of Radovan Karadzic," the prosecutor said in a statement in The Hague, the seat of the UN tribunal.

"On behalf of the Office of the Prosecutor, I would like to congratulate the Serbian authorities, especially the National Security Council, Serbia's Action Team in charge of tracking fugitives and the Office of the War Crimes Prosecutor, on achieving this milestone in cooperation with the ICTY."

One of the top war crimes suspects in the Balkans, Karadzic, is seen widely as a murderous megalomaniac with a twisted view of history and his supposed destiny as a leader of the Bosnian Serbs.

Bosnian Croats and Muslims, against whom Karadzic, 60, waged a barbaric campaign of "ethnic cleansing" in the early 1990s, have no doubt that he is one of the monsters of the 20th century.

But for many Serbs he remains a hero of the 1992-95 war which followed Bosnia's independence from the Yugoslav federation, a man who stood up to age-old enemies and great powers and carved out a separate Serb homeland.

So powerful was his underground network of supporters and loyalists, NATO-led peacekeepers responsible for his arrest were accused for years of gingerly tiptoeing around his most likely haunts as they launched "raids" that always seemed to produce nothing.

The worst crimes on his indictment are the 43-month siege of the Bosnian capital, Sarajevo, in which some 10,000 civilians were killed, and the massacre of more than 7,000 Muslim males in the eastern Bosnian town of Srebrenica in July 1995.

In the bitter war against Bosnia's Muslim-led government, he is said to have authorised "ethnic cleansing" in which more than a million non-Serbs were driven from their homes in villages where they had lived for generations.

The expulsions were accompanied, according to international observers, by widespread killings and up to 20,000 rapes in a calculated programme of terror that left the international community both shocked and impotent to respond.

Karadzic, with his thick shock of grey hair, became a familiar sight to television viewers around the world in the 1990s, when his contempt for diplomacy and cynical manipulation of United Nations' peacemaking efforts exasperated foreign negotiators.

He was a close ally of then-Serbian president Slobodan Milosevic, and the pair cooperated militarily and politically to confuse the Serbs' enemies, not just on the battlefields but also in the halls of diplomacy.