Secretary-General Ban Ki-moon on Monday called on Palestinians in Gaza with knowledge of two missing Israeli civilians to provide information about their possible whereabouts and conditions.
U.N. spokesman Stephane Dujarric said the secretary-general also called for prompt action to facilitate their safe return to their families.
Israeli defense officials identified one of the men as Avraham Mengistu, an Israeli of Ethiopian descent in his late 20s who disappeared after he "independently" entered Gaza on Sept. 7, 2014, two weeks after the end of Israel's war with Hamas, the Palestinian faction that controls Gaza.
Israel said the second man was a Bedouin Arab citizen from southern Israel but refused to identify him or say how long he had been in Gaza or how he got there.
Dujarric said "the secretary-general underscores the responsibility of all parties to protect and respect the rights of civilians."
He said the United Nations will continue to closely monitor developments.
Israeli Prime Minister Benjamin Netanyahu said last week he held Hamas, which has ruled Gaza since 2007, responsible for the fate of both men. He said Israel is working to free them.
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