PARIS — President Boris Tadic of Serbia announced at a news conference in Belgrade on Thursday that Ratko Mladic, the fugitive accused of masterminding the massacre at Srebrenica in 1995, had been captured but refused to give details.

Mr. Mladic, a former Bosnian Serb general, was one of the world’s most wanted criminals, evading capture for more than 15 years despite an increasing international effort to hunt him down. Serbian news reports said that he was living under the name of Milorad Komadic and that he was captured after a tip that he had identification documents for Mladic and appeared physically similar.

Mr. Mladic was blamed for the worst ethnically motivated mass murder on the Continent since World War II, which resulted in the massacre of about 8,000 Muslim men and boys from the Bosnian town of Srebrenica.

“Extradition is happening,” Mr. Tadic said. “This is the end of the search for Mladic. It’s not the end of the search for all those who helped Mladic and others to hide and whether people from the government were involved.”...