Opposition leader Anwar Ibrahim has condemned the air strikes conducted by Israel in Gaza during the Muslim holy month of Ramadan.

Hostilities between Israel and Hamas escalated on Tuesday, raising the death toll in two days to 32 Palestinians and three people in Israel, with Israel carrying out multiple air strikes in Gaza and the militant group firing rockets at Tel Aviv.

A 13-storey residential building in Gaza collapsed after it was hit by an Israeli air strike, one of hundreds that Israel said it had carried out against Hamas targets.

They were the most intensive aerial exchanges between Israel and Hamas since a 2014 war in Gaza, and prompted international concern that the situation could spiral out of control.