The United Nations has acknowledged that its facilities in the Gaza Strip were storing Palestinian missiles and rocket.

The UN Relief and Works Agency has reported at least two incidents in which its schools were used for the storage of rockets amid the war with Israel. The UN refused to confiscate the rockets and instead asked Hamas to retrieve the weapons.

“UNRWA strongly and unequivocally condemns the group or groups responsible for this flagrant violation of the inviolability of its premises under international law,” UNRWA said.

On July 22, the UN said it found rockets concealed in one of its vacant schools in the Gaza Strip. The UN did not say how many rockets were found or what was done with them.

“Today, in the course of the regular inspection of its premises, UNRWA discovered rockets hidden in a vacant school in the Gaza Strip,” the agency said. “As soon as the rockets were discovered, UNRWA staff were withdrawn from the premises, and so we are unable to confirm the precise number of rockets.”

Western diplomats, however, said the UN returned as many as 20 rockets to Hamas. Canada has called for an investigation of the UN action.

“I was appalled to hear reports, one as recent as today, of stockpiles of rockets in a school run by the United Nations Relief and Works Agency in Gaza,” Canadian Foreign Minister John Baird said. “Even more alarming were reports that in the first case, officials with the United Nations returned these weapons to Hamas, a listed terrorist organization, once Israeli officials discovered their location.”

The UN statement supported assertions by the Israeli military that Hamas and its Palestinian militia allies were using schools and mosques for rocket storage and attacks. In a report in mid-July, the UN said the Israeli military has been providing warning before attacks on civilian facilities believed to contain weapons.

“Hamas has dug terrorist tunnels under hospitals, mosques, schools, homes, to penetrate our territory, to kidnap and kill Israelis,” Israeli Prime Minister Binyamin Netanyahu said on July 22.

The latest rockets were found between two other UN schools that sheltered 1,500 Palestinians who fled their homes during the current war. The UN said the concealment of rockets marked a “flagrant violation of the inviolability of its premises under international law.”

“The agency immediately informed the relevant parties and is pursuing all possible measures for the removal of the objects in order to preserve the safety and security of the school,” the UN said. “UNRWA will launch a comprehensive investigation into the circumstances surrounding this incident.”