At least 93 people were killed in Israeli air strikes on the city of Beit Lahia, in northern Gaza, early on Tuesday, with rescue workers searching the rubble for dozens reported missing.

Twenty-five children were among the dead, the Gaza Health Ministry said.

The strikes hit a five-storey residential building housing about 150 displaced people, Palestinian media reported.

Israeli forces began a siege of northern Gaza more than three weeks ago, blocking the entry of aid and medical assistance. Israel has said its goal is to eradicate the operational infrastructure of Hamas.

Many of those injured on Tuesday were taken to the nearby Kamal Adwan Hospital, said Dr Marwan Al Hams, director of field hospitals at the Health Ministry.

“Anyone with medical skills or first aid training is urged to head to Kamal Adwan Hospital to help save the injured,” Dr Al Hams said.

Last week, Israeli troops raided the hospital, causing extensive damage and detaining several medical staff. The building was hit with prolonged artillery shelling on Tuesday morning, the Wafa news agency reported.

It added that dozens of people were still trapped under rubble after the latest strikes, with civil defence and ambulance crews unable to reach them.

“There have been appeals and distress calls for civil defence personnel to save the lives of the wounded,” civil defence spokesman Mahmoud Basal told The National. “But the civil defence system has been completely disabled due to the ongoing Israeli aggression in northern Gaza and the arrest of several of its personnel.”

There was no immediate comment on the strikes from Israel's military. Hamas issued a statement condemning the attack. “The northern part of the Gaza Strip is being subjected to a campaign of ethnic cleansing and systematic displacement, in full view of the world,” the group said.

Israeli strikes were also reported in Gaza City on Tuesday, with five people killed and more than 20 injured during two raids on a crowded market in the Al Daraj neighbourhood, Wafa reported. Several people were injured in an attack on a home sheltering a displaced family. Israeli forces also reportedly burnt down a UN-run school in the northern Jabalia refugee camp.

Two deaths were reported in southern Gaza when an Israel strike hit the Khirbet Al Adas area, north of Rafah city. Overall, at least 115 people were killed in Israeli attacks on Tuesday, Wafa quoted medical sources as saying.

The World Food Programme warned on Tuesday that the siege on northern Gaza increased the threat of famine in the enclave. The UN agency said it had about 94,000 tonnes of food in Egypt and Jordan that could feed one million people for four months, but this could not be moved into Gaza because of border restrictions and safety fears.

"Restrictions on humanitarian aid coming into Gaza are severe," the WFP said. Only 5,000 tonnes of supplies had entered the enclave this month, it added.

The need for Israeli authorities to issue approval for lorries and drivers to enter Gaza, as well as delays at checkpoints in the enclave, were exacerbating the crisis, the WFP said.