Bosnian and Serb police have made 15 arrests suspected of committing a war crime in 1993.
The incident during the Bosnian war saw Bosnian Serbs attack a train in the town of Strpci, near the Serbian border, killing 19 people, including 18 Bosniaks. The victims are reported to have been hauled of the train, tortured and shot, before their bodies were thrown into a river.
Five of the arrests were made in Serbia, with the remainder detained by Bosnian police, after a joint investigation. Senior figures in the former Bosnian Serb army were amongst the arrested, including Gen Luka Dragicevic, who led troops in the border zone.
According to reports, Yugoslav officials were warned by the Belgrade Railway Company (ZTP), that Bosnian Serb paramilitaries would stop the train and kidnap passengers.
"There existed at least a tacit agreement... I mean that some state organs took part," said Serbian Deputy War Crimes Prosecutor Bruno Vekaric, quoted by the Associated Press news agency.