The former Yugoslav President, Slobodan Milosevic, has been arrested.
A source close to the Serbian government said Milosevic had been arrested and would be transferred to a justice administration building in central Belgrade.
"He has been arrested and he should be brought to the palace of justice", the source said.
Belgrade's B92 radio station also reported the arrest, citing well-informed sources.
Mr Milosevic and four of his allies have been indicted by the International Criminal Tribunal for the former Yugoslavia in the Hague for war crimes allegedly committed in Kosovo in 1999.
The reports come after a day of activity at the former leader's home in Belgrade.
Hundreds of Belgrade citizens loyal to ousted president Slobodan Milosevic rushed to his house this evening in an attempt to protect him after a leading member of his party said his arrest was imminent.
Chanting "Slobo, Slobo," up to 300 people gathered around the walled compound which houses Milosevic's residence and a number of others, after a senior Socialist Party MP had railed in parliament against what he termed a police raid on his house.
Tension rose after five unmarked jeeps containing men wearing olive fatigue jackets and black ski caps were spotted late Friday outside the villa of the former president, who has been indicted by a UN war crimes court for his force's crackdown in Kosovo in 1999.
Two of the jeeps, an ambulance and police car were parked inside the compound, but at the opposite end to Milosevic's residence.
Three more were parked in a nearby side street of the well-heeled suburb of Dedinje.
"According to information we received, six vehicles with special police and an ambulance are in front of Uzicka street with the intention of arresting Slobodan Milosevic," Ivkovic said earlier in a protest statement to parliament, before rushing to join the crowd gathering outside his house.
Ivkovic held a meeting inside the house with the former president, emerging a little while later to say the man who ruled the country with an iron first for more than a decade was at home and unruffled by the alarm.
At least one end of the street was blocked off by uniformed policemen armed with automatic weapons who were preventing all vehicle access.
Ivkovic did not say what his source was for the alleged arrest tip-off.
Earlier in parliament, the head of the ultra-nationalist Serbian Radical Party (SRS) Vojislav Seselj, warned of possible unrest if the authorities send in the police.
"If there is bloodshed, an unending spiral of bloodshed could be started. I call for reason and I hope that among you there are reasonable people," said Seselj, a former Milosevic regime ally, in an appeal to the new government.
While he said he had "no reason to defend Milosevic" he warned the 18-party DOS coalition that "what you are doing is against the interests of the state."
Outside the Dedinje compound, the crowd chanted "If you are a Serb, come and join us."
Dozens of supporters of the fallen strongman have mounted a "people's guard" for weeks outside the residence, pledging to defend their hero if the police came for him.
In Washington, President George W. Bush said he was watching the situation in Belgrade and said the United States would "co-operate" if asked to do so.
The reformist authorities have come under increasing international pressure to extradite Milosevic to the International Criminal Tribunal for the former Yugoslavia (ICTY).
They have said the law prevents Yugoslav nationals being extradited. Until it is amended, many have insisted Milosevic should stand trial in Serbia.
The Yugoslav Interior Minister, Zoran Zivkovic, said he could neither confirm nor deny the report. More to follow...