Hamas' attempts to minimize attention on its strategy of using civilian areas as a base of operations for rocket fire and other terrorism took a hit Tuesday when a United Nations relief organization found rockets stored in one of their schools for the second time in a week.

UN Secretary General Ban Ki-moon issued a statement saying he was "alarmed and outraged" by the discovery of rockets in a vacant United Nations Relief Works Agency (UNRWA) school. He "calls on all of those who have any influence over militant groups to send an unmistakable message that this is unacceptable."

The UNRWA said it found the rockets "in the course of the regular inspection of its premises" Tuesday. Placing rockets in a UN building is a "flagrant violation of the inviolability of its premises under international law."

UNRWA condemnation of Palestinian groups' actions is extremely rare, emphasizing the severity of the recent incidents.

Speaking with the Times of Israel, Foreign Ministry spokesperson Yigal Palmor reacted intensely: "How many more schools will have to be abused by Hamas missile squads before the international community will intervene?"

"How many times can it turn its head the other way and pretend that it just doesn't see?"

Last week, the UNRWA discovered about 20 rockets in one of its schools during an inspection. A spokesperson for the agency said that the rockets were then transferred to "local authorities," which take orders from the ruling Hamas regime.

Israel is infuriated by the fact that a UN agency purportedly dedicated to humanitarian issues in Gaza transferred to a terrorist organization rockets which would likely be used to fire on Israeli civilians.

The UNRWA has a history of allowing Hamas use its facilities for its terrorist activities. "Time and again, over the years, UNRWA has been abused by gunmen from different terrorist factions who are using UN facilities to stockpile weapons, to fire rockets from, to steal UNRWA humanitarian equipment and to cause damage and fire in UNRWA's hangars," an unnamed senior foreign ministry official told the Times of Israel. "Against all evidence, UNRWA refuses to acknowledge reality and pathetically attempts to ingratiate itself with Hamas, pretending that nothing serious has happened."