UPDATE: Israeli strikes kill over 400 in Gaza

(Reuters) - Israeli airstrikes pounded Gaza, killing more than 400 people, Palestinian health authorities said on Tuesday (18), threatening the complete collapse of a two-month ceasefire as Israel vowed to use more force to free hostages held by Hamas.

The Palestinian militant group, which still holds 59 of the 250 or so hostages seized in its October 7, 2023 attack on Israel, accused Israel of breaching the ceasefire and jeopardising efforts by mediators to secure a permanent truce.

Israel's prime minister, Benjamin Netanyahu, said he had told the military to take "strong action" against Hamas in response to the group's refusal to release the remaining hostages and because of their rejection of ceasefire proposals.

Egypt, one of the mediators in the ceasefire deal agreed in January, called for restraint and urged all parties to work towards a lasting agreement.

Airstrikes hit houses and tent encampments from the north to south of the Gaza Strip and Israeli tanks shelled across the border line into the east and south of the enclave.

"It was a night of hell. It felt like the first days of the war," said Rabiha Jamal, 65, a mother of five from Gaza City.

"We were preparing to have something to eat before starting a new day of fasting when the building shook and explosions began. We thought it was over but war is back," she told Reuters via a chat app.

In hospitals strained by 15 months of bombardment, piles of bodies in white plastic sheets smeared with blood could be seen stacked up as casualties were brought in. Gaza's Hamas-run health ministry said 404 people had been killed, many of them children, and 562 people were injured.

The Israeli military said it hit dozens of targets, and that the attacks would continue for as long as necessary and extend beyond airstrikes, raising the prospect that Israeli ground troops could resume fighting.