Tolimir, indicted by the UN tribunal in The Hague, was a senior aide to the Bosnian Serb wartime military commander, General Ratko Mladic, during the slaughter of up to 8,000 Bosnian Muslims in Srebrenica in 1995 - the worst carnage in Europe since World War II.
Tolimir - who was reported to have organised Mladic's escape from justice - was arrested after a major security sweep of the border region that included helicopters and anti-terrorist units, said the Serbian officials, speaking on condition of anonymity because they were not entitled to release the information before Tolimir is sent to The Hague.
Tolimir is considered by UN war crimes prosecutors as the third most wanted fugitive after Mladic and Bosnian Serb wartime political leader Radovan Karadzic, who are both still at large.
As a ranking intelligence and security officer during Bosnia's 1992-95 war, Tolimir was charged by the UN tribunal with four counts of crimes against humanity, including murder, persecution on political, racial and religious grounds, and other inhumane acts.
The charges say that he "committed, planned, instigated, ordered, and otherwise aided and abetted in the planning, preparation, and execution of the crimes" against non-Serbs during the war, including in Srebrenica.