A UN inquiry has found that at least 44 Palestinians were killed and at least 227 injured by direct mortar strikes and other "Israeli actions" while sheltering at UN locations during last year's Gaza war. The Palestinians said they would give the findings to the International Criminal Court.

The independent board of inquiry also said that Palestinian militant groups hid weapons at three empty UN schools in Gaza and that in two cases Palestinian militants "probably" fired from the schools.

UN Secretary-General Ban Ki-moon said Monday that he deplores the deaths, calling UN locations "inviolable." Ban also said the Palestinian militants' use of them was "unacceptable."

The 2014 war was the most devastating for Gaza's 1.8 million people, killing more than 2,200 Palestinians, a majority of them civilians, according to UN figures. Seventy-two people were killed on the Israeli side, including 66 soldiers.

In one case, the new inquiry says, a UN girls' school was hit by 88 mortar rounds fired by the Israeli Defence Forces. In another case, another girls' school was hit by direct fire from the IDF with an anti-tank projectile. A third girls' school was hit by an IDF missile.

At a coed college, one block was damaged by a projectile fired by an Israeli tank.

On July 30, Israeli strikes tore through the walls of the Jebaliya Elementary girls' school, which was crowded with sleeping war refugees. Some 3,000 Gazans had sought refuge there. A series of Israeli artillery shells hit before daybreak. A classroom became a scene of bloodied clothing, bedding and debris. The inquiry says 17 or 18 people were killed, including a UN staff member and two of his sons.

"No prior warning had been given by the government of Israel of the firing of 155 MM high explosive projectiles on, or in the surrounding area of the school," the inquiry says.

A spokesman for the UN agency for Palestinian refugees said in a statement, "The inquiry found that despite numerous notifications to the Israeli army of the precise GPS co-ordinates of the schools and numerous notifications about the presence of displaced people, in all seven cases investigated by the Board of Inquiry when our schools were hit directly or in the immediate vicinity, the hit was attributable to the IDF."

Spokesman Chris Gunness added, "In none of the schools which were hit directly or in the immediate vicinity, were weapons discovered or fired from."

The inquiry also found weak security at the UN schools where weapons were found. It said in two cases that a "Palestinian armed group" likely fired from two of the schools.

The UN released its summary of the report but said the full 207-page report is private. The inquiry looked at 10 incidents. Ban's statement stressed that the board of inquiry "does not make legal findings" and was not tasked with addressing the wider issues of the Gaza war.

Palestinian Foreign Minister Riad Malki said, "We will take the report and will present to the International Criminal Court, especially that they are looking these days at our request to do a preliminary study." The Palestinian Authority became a member of the court this month in an effort to pressure Israel..

Malki also praised the UN for releasing the report after a delay, saying he had been worried that Israel was trying to suppress it.

In a statement, Israeli Foreign Ministry spokesman Emmanuel Nahshon said, "All of the incidents attributed by the report to Israel have already been subject to thorough examinations, and criminal investigations have been launched where relevant. ... Israel makes every effort to avoid harm to sensitive sites."

Nahshon's statement added, "The executive summary of the report clearly documents the exploitation by terrorist organizations of UN facilities in the Gaza Strip."

Sami Abu Zuhri, a spokesman for Hamas, the militant Islamic group that rules Gaza, said the UN report was a "clear condemnation" of Israel. On reports that militants used UN schools to store weapons he said: "Hamas has no information about this."