Serbian President Boris Tadic is due to visit a wartime atrocity site in Croatia this week to pay respects to Croat hospital patients killed by Serb forces during the 1991 war.
Tadic will be the first Serbian leader to pay his respects to the victims of the massacre at Ovcara, where more than 200 Croats were killed.
Tadic and Croatian President Ivo Josipovic will also honor 18 Serbs killed by Croats in a nearby village.
During the war, Serbia backed ethnic Serbs in Croatia who fought against Croatia's independence from Serb-led Yugoslavia.
Belgrade and Zagreb have improved relations since the war, but arguments over responsibility for wartime crimes remain.
compiled from agency reports