The US government has expressed serious concern about the steep rise in civilian casualties in the Gaza Strip in the last few days.

State Department spokesperson Matthew Miller said on Monday that Secretary of State Antony Blinken conveyed Washington's "serious concern about the recent civilian casualties in Gaza" in a meeting with Israeli officials.

He said the US is "pushing so hard to a ceasefire."

On Tuesday, Israel continued its air raids and ground offensives in many areas across the enclave. Palestinian media reported that four died in residential blocks in the southern city of Rafah.

Public health authorities in Gaza said at least 90 people were killed in Saturday's air raids that reportedly targeted the top military official of Hamas. They also said that, on Sunday, 22 people died in an air raid on a school where many residents were sheltering.

There's also a report that a municipality where hundreds of thousands of people have taken refuge can no longer provide them with drinking water, as fuel has run out to operate water purification systems.

Israel and Hamas remain wide apart in ceasefire talks. Israel aims to destroy Hamas, while the Islamic group seeks a permanent ceasefire and the withdrawal of the Israeli military from the enclave.