Bosnian police on Tuesday arrested eight Bosnian Serbs suspected of killing around 120 Bosnians and Croat men and boys in northwest Bosnia at the start of the 1992-95 war.
The operation was carried out on the orders of the state war crimes prosecutor, the prosecutor's office said in a statement.
The men are suspected of crimes against humanity committed during a wide and systematic attack by Serb army, police and paramilitaries in the Prijedor region, it added.
"The group are believed to have illegally detained 120 men, including 15 boys, in the village of Miska Glava, and taken them to a nearby cultural center and a stadium where they were tortured and abused for three days," the statement read.
Up to 15 detainees were executed at these locations while the remainder were taken to the town of Ljubija and shot dead.
"Only a few victims survived the execution and their testimonies were of key importance in shedding light on this atrocity," the statement added.
The Prijedor region was a stronghold of ultra-nationalist Serb forces who killed thousands of Muslim Bosnians and Catholic Croats there and drove tens of thousands out of the region.
Some were killed in Serb-run detention camps and others in their homes.
Seventeen Bosnian Serbs, including wartime leader Radovan Karadzic, have been convicted by the Hague-based international war crimes tribunal over events in the Prijedor region.
More than 80 people have been sentenced in the Hague for crimes dating from the 1990s conflicts in former Yugoslavia.
The bodies of victims in the case that led to the eight arrests on Tuesday were exhumed from two mass graves in the Prijedor region soon after the Bosnian war ended, and from a third discovered only this year, the prosecutor's office said.
An estimated 100,000 people died in the Bosnian war.