A former president of Bosnia-Herzegovina, Ejup Ganic, was arrested in London for alleged war crimes and was to stay in custody until a further hearing at the end of March, Scotland Yard said on Monday.
Britain's Foreign Office confirmed the arrest, but said in a statement: "As the case is now before the courts, it would be inappropriate to comment further at this time."
Scotland Yard said the 63-year-old was picked up at London's Heathrow airport as he was preparing to leave Britain after a provisional extradition warrant was issued by the Serbian government.
Ganic was detained at about 1400 GMT Monday and appeared before the City of Westminster Magistrates Court in the afternoon. He was remanded in custody to reappear at the court on March 29.
The Serbian authorities are now expected to file papers to support their extradition request before a date for an extradition hearing can be fixed.
The Serbian Interior Ministry had in early 2009 issued arrest warrants for Ganic and 18 others over an attack on a Yugoslav Army convoy in Sarajevo in May 1992 in which 42 soldiers were killed and 73 wounded.
The news of Ganic's arrest came hours after former Bosnian Serb leader Radovan Karadzic delivered his opening statement before the war crimes tribunal in The Hague and defended the 1992-1995 Bosnian war as "just and holy."
Member of the Bosnian tripartite presidency Haris Silajdzic told Bosnian media that Ganic's arrest is "an attempt to equalize the guilt."
The Muslim-Croat Federation of Bosnia and Herzegovina claims that Serbia and the Yugoslav Army initiated the Bosnian war and were the aggressors.
Ganic, who was president and vice-president of the Federation of Bosnia and Herzegovina from end-1997 to 2001, is accused of alleged conspiracy to murder wounded soldiers in breach of the Geneva Convention, Scotland Yard said.
After the war, Bosnia was divided into two largely autonomous entities - the Serb Republic and the Muslim-Croat Federation.