Mr. Mladic, a former Bosnian Serb general, was one of the world’s most wanted criminals, evading arrest 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,” Boris Tadic, the Serbian president said, referring to the international war crimes tribunal in The Hague. “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.”
Radovan Karadzic, the Bosnian Serb political leader and Mr. Mladic’s boss, is currently being tried in The Hague on charges of genocide for his role in the Balkan bloodshed. Slobodan Milosevic, the former president of Serbia and the architect of the war, died in 2006 while his trial was under way.
A lawyer for Mr. Karadzic said the arrest announced on Thursday could have serious implications for Mr. Karadzic’s trial. Peter Robinson said that the court may decide to try Mr. Mladic and Mr. Karadzic together.
Mr. Tadic stressed that “this is happening on the day Catherine Ashton is coming to Serbia,” a reference to the European Union’s foreign policy chief. The arrest of Mr. Mladic and the continuing dispute over Kosovar secession from Serbia remain the largest stumbling blocks to Serbia’s moving forward with its bid to become a member of the European Union.
Mr. Tadic gave no other details, other to say that Mr. Mladic was arrested “on Serbian soil,” but several Serbian news outlets reported that he was arrested early Thursday morning in Vovjodina, a province of northern Serbia.
Though the public response was unclear, Ljiljana Smajlovic, president of Serbia’s Journalists Association, said she did not expect political unrest or rioting to break out. “The weight of evidence against Mladic is staggering, even if Serbs remain unconvinced that the Hague tribunal has been evenhanded in its approach to war criminals in the former Yugoslavia,” she said.
Ms. Smajlovic said that the fact that Ms. Ashton was in Serbia on Thursday meeting with Serbian officials would “lead to suspicion that the arrest was timed to honor her and also to underline Serbia now has high expectations of rapid E.U. integration.”
In response to a question, Mr. Tadic said: “ I do not expect that Serbia because of this arrest will be destabilized. Whoever tries to make any troubles will end up in court.” He said that the last remaining Serbian fugitive, Goran Hadzic, “will be arrested. I promise it is going to happen.” Mr. Hadzic is wanted in connection with the massacres of Bosnian Croat.
Mr. Tadic added that three years ago, his government had created “an action team and they delivered.”
Mr. Mladic had been in hiding since 1995, widely believed to be protected by allies in the Serbian military and intelligence.
The arrest comes at a crucial moment, just days before the release of a report by the Serge Brammertz, the chief prosecutor of the United Nations war crimes tribunal in The Hague, that was expected to say that Serbia was not cooperating and that it had ignored his latest outline of how to catch the so-called fugitive. The report would have effectively blocked Serbia’s chances to become an official candidate for the European Union. The Netherlands, which hosts the court and whose peacekeepers were overrun by Mladic’s troops at Srebrenica, had said it would veto Serbia’s candidacy without the arrest of Mr. Mladic, thereby puncturing the required consensus.
Frederick Swinnen, an official at the prosecutor’s office in The Hague, said by telephone that Mr. Mladic was expected there soon, but that the “process of surrender” would take several days.
Sometimes hiding in plain sight at soccer matches and sometimes deep in the fabric of this secretive city, Mr. Mladic appeared to have spent recent years hidden by no more than a handful of loyalists, investigators and some of his past associates have said.
The former leader of the armed forces of the Bosnian Serbs during the Balkan wars of the early 1990s was thought to be last living in New Belgrade, a sprawling extension of the Serbian capital across the Sava River. His diminished circumstances appeared to make him ripe for capture.
Semir Guzin, a lawyer for the Mothers of Srebrenica, an activist group representing survivors of the massacre, told the BBC that with the arrest, “Justice is done. I hope Mr. Mladic will get what he deserves.”
Over the years, as European pressure for an arrest intensified and then retreated, he received vital, little-known assistance from Serbian military forces and several of the country’s past governments as recently as 2008.
J. David Goodman contributed reporting from New York.