Bosnian Serb general Ratko Mladic was arrested in Lazarevo, a village in northern Serbia, where he was staying with a relative, the Serbain national television RTS said.
The authorities did not divulge any details of Mladic's arrest, but witnesses told RTS that at 5:30 am (0330 GMT), police raided the house of Mladic's relative, DPA reported.
The arrested man had an identity card in the name Milorad Komadic.
The villagers insisted that they never saw Mladic. Shoving broke out between some of the residents and reporters who swarmed Lazarevo, 60 kilometres north of Belgrade, in the wake of Mladic's arrest.
Mladic, 69, faces genocide charges at the International Criminal Tribunal for the former Yugoslavia for the 1995 massacre of 8,000 Muslims in Srebrenica and for the shelling and sniping of Sarajevo during the 1992-95 Bosnian war.