BELGRADE, July 21 (Reuters) - Bosnian Serb wartime president Radovan Karadzic, one of the world's most wanted men for his part in civilian massacres, has been arrested in Serbia, President Boris Tadic's office said on Monday.

The arrest of Karadzic and other indicted war criminals and their delivery to the Hague war crimes tribunal, is one of the main conditions of Serbian progress towards European Union (EU) membership.

It came on the eve of a meeting of EU Foreign Ministers which is scheduled to discuss closer relations with serbia following the formation of a new pro-western government. A war crimes prosecutor was due to visit Belgrade on Tuesday.

Karadzic's place of hiding has been a constant subject of international speculation since he went underground in 1997. Sources close to the government said Karadzic, distinguished by his characteristic long, grey hair, was arrested in Belgrade.

He was currently undergoing a formal identification rocess, inccluding DNA testing, and would be meeting with investigators overnight.

"Karadzic was located and arrested," the President's statement said. It gave no details.

Karadzic, was leader of the Bosnian Serbs during the 1992-95 Bosnia war. He was indicted by the United Nations war crimes tribunal in The Hague in July 1995 for authorising the shooting of civilians during the 43-month siege of Sarajevo.

He was indicted for genocide a second time four months later for orchestrating the slaughter of some 8,000 Muslim men after Mladic's forces seized the U.N. "safe area" of Srebrenica in eastern Bosnia.

He went underground in 1997 after losing power.

source: NY Times