United Nations Humanitarian Affairs Chief John Holmes blasted Hamas Tuesday for its "cynical" use of civilian facilities during recent hostilities in the Gaza Strip.

"The reckless and cynical use of civilian installations by Hamas and indiscriminate firing of rockets against civilian populations are clear violations of international humanitarian law," Holmes told the UN Security Council.

Israel came under harsh criticism from the UN for firing on its facilities during Operation Cast Lead. Israel says Palestinian gunmen used the facilities as bases from which to attack its troops. According to Palestinian sources, bombings of UN facilities killed nearly 50 people in Israel's three-week long offensive in the Gaza Strip.

Holmes added that Hamas must not interfere with the movement of humanitarian supplies and urged Israel to reopen the border crossings to allow large quantities of humanitarian aid into the Gaza Strip.

"Israel has a particular responsibility as the occupying power in this context, because of its control of Gaza's borders with Israel, to respect the relevant provisions of international humanitarian law," he said.