US President Joe Biden on Wednesday pressed Israeli Prime Minister Benjamin Netanyahu on the urgency of sealing a deal for a truce in Gaza and the release of hostages, the White House said, but Israel and Hamas stuck firmly to their demands.

The call between the leaders, in which Vice President Kamala Harris also took part, came after Palestinian health officials reported at least 50 Palestinians killed by Israeli airstrikes over a 24-hour period.

Biden stressed to Netanyahu "the urgency of bringing the ceasefire and hostage release deal to closure and discussed upcoming talks in Cairo to remove any remaining obstacles," a White House statement said.

US, Israeli, Egyptian, and Qatari negotiators, who are expected to meet in Cairo this weekend, have for months struggled to bridge differences between Israel and Hamas.

But Israel and Hamas on Wednesday held to their demands.

"Israel will insist on the achievement of all of its objectives for the war, as they have been defined by the Security Cabinet, including that Gaza never again constitutes a security threat to Israel," Netanyahu's office said in a statement.

Denying an Israeli television report, it said Israel had not agreed to drop its demand to maintain troops in the Philadelphia Corridor, the border strip between Gaza and Egypt, an issue that has been a major sticking point.

A Hamas statement said its officials, meeting with the head of Palestinian Islamic Jihad about progress in the talks, reiterated key Hamas demands. These include an end to Israel's Gaza operation, a full Israeli pullout and a deal to exchange Israeli hostages for Palestinian prisoners held by Israel.

The call between Biden and Netanyahu followed a whirlwind trip to the region by US Secretary of State Antony Blinken that ended on Tuesday without producing a breakthrough in the 10-month-old war.

In Gaza itself, the Israeli military said jets hit around 30 targets throughout the enclave including tunnels, launch sites and an observation post.

It said troops killed dozens of armed fighters and seized weapons including explosives, grenades and automatic rifles.

The Israeli military struck a school and a nearby house in Gaza City, killing at least four people and wounding 15, including several children, Gaza's Civil Emergency Service said.

The Israeli military said in a statement that it hit Hamas militants operating at a command centre inside a compound that previously served as a school.

It accused Hamas of continuing to operate from civilian facilities and areas, an allegation Gaza's dominant Islamist militant group denies.

Commenting on Israel's attack on the UN-run school, the head of the UN's Palestinian refugee agency, Philippe Lazzarini, wrote on X that "children reported killed and injured. Some were burnt to death."

"Gaza is no place for children anymore. They are the first casualty of this merciless war," he wrote. "A ceasefire is beyond overdue."

In the town of Bani Suhaila near Khan Younis in the southern Gaza Strip, an Israeli airstrike killed seven Palestinians at a tent encampment for displaced people, medics said.