Of a total of 6,065 cases of missing persons disappeared in connection with the war in 1998-1999, 1,607 remain unresolved.
The new agreement means that a working group is established to implement the declaration adopted by Serbian President Aleksandar Vucić and Kosovo's Prime Minister Albin Kurti last year. Tuesday's agreement in Brussels is seen as a success as it comes at a time of increased tensions between the countries, including violent clashes.
According to the 2023 declaration, the parties will work closely together to identify grave sites.
They also promise to provide each other with full access and reliable and correct information in the work of finding and identifying the missing persons.
The search work is led by the International Red Cross Committee.
