Five tons of unexploded Israeli bombs stored in the Gaza Strip under Hamas police guard are missing and believed stolen, U.N. spokesman Richard Miron said.
He said a U.N. disposal team had intended to disarm them.
The bombs were dropped during Israel's Gaza offensive that ended last month, another United Nations official said.
Israeli military spokesman Peter Lerner said the explosives were probably taken by Hamas to another location. Hamas officials said they had no knowledge of the matter.