Over 100 000 people around the world are missing, which has created a global "crisis", the International Committee of the Red Cross said on Monday.
Agnes Coutou, the organisation's protection adviser, told the UN General Assembly's human rights committee that "this is the highest number we have ever had".
"We know that this is the tip of the iceberg and that it represents only a fraction of those estimated to be missing because of past and ongoing conflicts," she said.
The International Committee of the Red Cross works with the families of missing persons and authorities in over 40 countries affected by past and current conflicts. It also chairs five bodies trying to resolve cases of missing persons.
Coutou said three factors driving the crisis are the scale of armed conflicts responsible for a substantial number of missing; the "intergenerational impact" of people missing for decades on their families; and the increased internationalisation of the problem.
"Missing persons shape the history of families, communities and societies profoundly," she said. "Such unresolved consequences of conflict that stretch over decades can hamper the prospects of peace."
Coutou said today's wars involve individuals and groups from a variety of countries, which multiplies the number of people affected and involved in missing person cases.
"The transnational dimension of the question of missing persons is particularly clear in its overlap with migration, as thousands and thousands of people fleeing conflict also go missing in transit and destination countries," she said.
Coutou said the International Committee of the Red Cross is calling for "early and preventive action" to keep people from going missing, "whether they are alive or dead". This means registering all people who are detained, enabling them to contact their families, registering and centralising information on all those missing, ensuring identification of human remains, and protecting gravesites, she said.
Coutou said the organisation is also calling for upholding families' right to know the fate and whereabouts of missing relatives and exchanging good practices and tapping into expertise on the missing.
She expressed hope that many UN member nations will respond and "help some of those who so desperately wait for news of their loved ones".
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