BBC reported Tuesday that the cache included aircraft bombs and white phosphorus shells.
United Nations officials said they were trying to determine where the munitions were taken. Israel has accused Hamas of taking the stockpile, which was under Hamas guard.
"We are anxious to get the return of this ordnance. It's clearly extremely dangerous and needs to be disposed of in a safe manner," said U.N. spokesman Richard Miron. "This is our primary concern."
The British news network reported a United Nations mine demolition team has been in Gaza since the end of the Israeli-Palestinian fighting last month trying to dispose of unspent Israeli artillery shells.