The International Committee of the Red Cross (ICRC) has said more than 13,000 people are still missing from the 1990s Balkans wars.
Barbara Hintermann, a top ICRC official, urged authorities in Zagreb and Belgrade to intensify efforts to find the missing.
She said the main problem the ICRC encounters is that authorities do not share information about possible mass grave sites.
In addition, there is a backlog in the identification of remains, with hundreds waiting in mortuaries across Croatia while hundreds more sets of remains have yet to be exhumed.
According to the ICRC, out of the more than 13,000 still missing nearly 9,000 are related to the conflict in Bosnia-Herzegovina, nearly 2,500 are related to the war in Croatia, and the rest to the war in Kosovo.
With reporting by AFP