Israel kept up its air strikes on Gaza Wednesday after Prime Minister Benjamin Netanyahu vowed to ramp up the pressure on Hamas as hopes fade for a US-announced ceasefire plan.

Hamas political leader Ismail Haniyeh accused Israel of deliberately undermining negotiations for a truce and hostage release deal because it did not want to end the war, reports AFP. The Israeli military says it carried out 25 strikes in 24 hours, targeting 'military structures, terrorist infrastructure, terrorist cells and rigged structures'.

It said its troops were also "continuing precise, intelligence-based operational activity" around the southern Gaza city of Rafah. Netanyahu, who has repeatedly vowed to destroy Hamas, insisted Tuesday that despite the pressure Israel was coming under, there could be no let-up in Israel's campaign against the Hamas. "This is exactly the time to increase the pressure even more, to bring home all the hostages -- the living and the dead -- and to achieve all the war objectives," he said.

The health ministry in Hamas-ruled Gaza said 52 people, most of them women and children, had been killed in Israeli strikes over the previous 24 hours. The UN humanitarian office OCHA said multiple strikes across Gaza on Tuesday killed and wounded dozens.

The territory's civil defence agency said 30 people had been killed in three strikes in Nuseirat refugee camp in central Gaza, one on a UN-run school, another on a house and a third on a mosque.