GENEVA: Israel's recent barrage of deadly airstrikes on Gaza might be war crimes, the UN rights chief warned Thursday, adding she had seen no evidence the attacked buildings were used for military purposes.

"If found to be indiscriminate and disproportionate impacting on civilians and civilians' objects, such attacks may constitute war crimes," Michelle Bachelet told a special session of the UN Human Rights Council.

"Despite Israel's claims that many of these buildings were hosting armed groups or being used for military purposes, we have not seen evidence in this regard," she said.