At least 70 killed in Israeli strike on Gaza's Beit Lahia

Residential building flattened in northern city, with most of the dead reported to be children

People check the rubble of a building hit by an Israeli strike in Beit Lahia, northern Gaza. AFP

Live updates: Follow the latest on Israel-Gaza

At least 72 people were killed and dozens more wounded by an Israeli air strike on a residential building hosting displaced families in the city of Beit Lahia in northern Gaza on Sunday, local authorities said. The attack took place just hours after separate Israeli air strikes killed 14 people in the nearby Bureij and Nuseirat refugee camps.

A five-storey building housing at least six families from elsewhere in the enclave collapsed following the strike in Beit Lahia, according to official Palestinian news agency Wafa, which described it as a "bloodbath". Continuing Israeli attacks and the extent of the damage were preventing rescue teams from reaching the area, said Wafa, which reported that most of the dead were children.

There were conflicting reports on the death toll, with Gaza's government media office saying 72 were dead, while Wafa reported at least 50 killed. Wafa said 70 people were believed to have been in the building at the time of the attack. The number of casualties was expected to rise, with reports of several people missing.

Images from the site showed civilians on top of an immense mound of rubble where the building once stood, combing through the flattened remains for victims. A lengthy Israeli military siege on northern Gaza has decimated efforts to rescue people caught up in Israeli bombings and left the area with no functioning ambulances, meaning the ability of paramedics and civil defence teams to carry out their work is limited.

Israel's army said there were "ongoing terrorist activities in the area of Beit Lahia", adding: "Overnight, several strikes were conducted on terrorist targets in the area."

"We emphasise that there have been continuous efforts to evacuate the civilian population from the active war zone in the area," the ministry said in a statement.

More than 2,000 people have been killed and 6,000 wounded in the siege, now in its 44th day, Wafa reported on Sunday. Israel has stepped up its air strikes, deployed ground troops and tanks and prevented aid from entering the north in what it says is a bid to prevent the militant group Hamas from regrouping in the area.

The siege has left trapped civilians "waiting to die", according to UN officials, and also prevented thousands of children from receiving a second dose of polio vaccinations. The entire northern population is at "imminent risk of death", the heads of 14 UN agencies warned earlier this month, describing conditions in the area as apocalyptic.

The Organisation of Islamic Co-operation condemned Israeli actions against a UN school and "indiscriminate" shelling of the Beit Lahia and Al Nuseirat areas this week.

It called on the international community, "especially the UN Security Council, to assume its responsibilities towards stopping the war crimes and massacres committed by the Israeli occupation, and to ensure the adequate and sustainable entry of humanitarian aid to all parts of the Gaza Strip, especially the northern part of the Strip, which is under a tight blockade, as well as to provide international protection for the Palestinian people," the Saudi Press Agency reported.