Government spokesman Srdjan Djuric tonight denied unofficial information that Mladic was arrested.
"This is harmful manipulation which does not contribute to the Serbian government's efforts to complete its cooperation with the Hague tribunal," he said in a press release.
The dpa news agency quoted Serbian Interior Ministry spokeswoman Dragana Kajganic as saying that the police "today did not undertake any operation" to arrest Mladic.
This afternoon, some Serbian media, including the Tanjug news agency and the B92 radio station, carried information by TV BN from Bijeljina in Bosnia-Herzegovina that Mladic was arrested and that he would be transferred to The Hague via Tuzla. Reuters, AFP and AP news agencies and the TV stations CNN, Sky News and Euronews carried the news, stating that it was unofficial and unconfirmed.
Former Serbian leader Slobodan Milosevic was transferred to the International Criminal Tribunal for the former Yugoslavia via Tuzla, Bosnia and Herzegovina, in 2001, aboard a plane from the nearby US base Camp Eagle.
In 1995 the UN court indicted Mladic for genocide committed during a 43-month siege of Sarajevo which claimed the lives of 12,000, and for commanding the killing of about 8,000 Muslims in Srebrenica. His political leader Radovan Karadzic is still at large.
Recently Serbian media were saying that Mladic would be aboard a plane to The Hague before the end of February so that a suspension of Belgrade's negotiations with the European Union could be averted.
The end of February is the final deadline by which EU Enlargement Commissioner Olli Rehn is due to submit a report based on which the Union will assess if Serbia is cooperating fully with the Hague tribunal.
The spokeswoman for the tribunal's Office of the prosecutor, Florence Hartman, said today she had no information about Mladic's arrest. Those are rumours, we cannot comment on something which does not exist, she said.
Not confirming newspaper allegations about an impending arrest, Serbian Prime Minister Vojislav Kostunica's advisor Vladeta Jankovic was quoted by Reuters as saying that efforts to locate Mladic were in full swing.
"The government is aware of the consequences," he told B92 radio. "This could be a decisive moment, not only for the future of the government but also for the future prospects of the state," he said, adding that Mladic's surrender was "almost a survival condition".
Belgrade is trying to avert the suspension of negotiations on stabilisation and associations which were launched last year. They are the first step towards possible membership of the EU, which is Serbia's top priority. Brussels has cautioned Belgrade that they will be stopped unless Mladic is arrested.
Reports predicting the arrest intensify every time Serbia faces a final deadline for action from the West, although Belgrade constantly complains that Mladic is not in the country.
Mladic openly lived in Belgrade until Milosevic's fall in 2000, when he lost the support he had enjoyed. Chief prosecutor Carla del Ponte persistently claimed that Mladic still enjoyed the protection of hardliners in the Serbian army and intelligence.
Serbian Human Rights Minister Rasim Ljajic said the moment was good to extradite Mladic, who is considered a war hero by the nationalist hardliners opposing his arrest. "The latest public opinion polls show that 57 per cent of citizens are in favour of that option," he said.