JERUSALEM (JTA) — United Nations Secretary General Ban Ki-moon said an independent Board of Inquiry will look into the cases of U.N. agencies hit by artillery during the Gaza conflict, as well as instances in which weaponry was found on UN premises.

He also questioned the “proportionality” of Israel’s response to rockets fired from Gaza.

Ban briefed the Security Council Tuesday on his recent visit to Gaza in the wake of this summer’s 50-day Gaza conflict.

“Nothing could have prepared me for what I witnessed in Gaza. I saw mile after mile of wholesale destruction,” Ban told the council.

More than 100,000 residents of Gaza remain homeless with over 50,000 sheltering in U.N.-run school buildings, according to the U.N.

Ban also visited the family of a four-year-old Israeli boy killed by a Hamas rocket, and a tunnel dug by the terrorist Hamas organization from Gaza to southern Israel.

“I fully understand the security threat to Israel from rockets above and tunnels below. At the same time, the scale of the destruction in Gaza has left deep questions about proportionality,” he said.

Ban called for “long-term stability in Gaza” which he said requires “addressing the underlying causes of the conflict: an end to the occupation that has grinded on for nearly half a century, a full lifting of the blockade on the Gaza Strip and effectively addressing Israel’s legitimate security concerns.”