Dozens of Palestinians, mainly children, have been killed in fresh Israeli strike targeting a residential building in Khan Younis.

The attack on Saturday morning marked a dramatic escalation of airstrikes on southern Gaza by Israel.

The director of the Nasser hospital was quoted as saying that the facility had received 26 dead bodies and 23 people with serious injuries after a strike on a residential building in the city of Hamad.

For the past 42 days, the Israeli military has been pounding northern Gaza, telling residents to flee to south.

The attack on Khan Youni came just after Israel issued warnings to Palestinians in the southern city to relocate west, indicating an attack was imminent.

With the conflict entering its 43rd day, the death toll in Gaza has now surpassed 12,000 Palestinians, with the majority of those killed being women and children.

Israeli troops on Saturday ordered the evacuation of al-Shifa Hospital in Gaza City "in the next hour" over loudspeakers as troops combed the facility, news agencies reported.

Al-Shifa Hospital -- Gaza's biggest -- has become the focus of Israeli attacks in its ruthless invasion of the city.

The United Nations estimated 2,300 patients, staff and displaced Palestinians were sheltering at al-Shifa before Israeli troops moved in on Wednesday.

The health ministry in Gaza has announced dozens of deaths there as a result of power cuts caused by fuel shortages amid intense combat.

Israel has made repeated calls for the hospital to be evacuated to the south, however medical professionals say the patients cannot be moved.

Hospital director Mohammed Abu Salmiya told AFP Israeli troops instructed him to ensure "the evacuation of patients, wounded, the displaced and medical staff, and that they should move on foot towards the seafront".

Forty patients at al-Shifa Hospital in northern Gaza have died since November 11 due to a lack of electricity, the UN Office for the Coordination of Humanitarian Affairs said.

In an interview with Al Jazeera Arabic, the general manager for the Palestinian Ministry of Health, Munir al-Barsh, said Israeli forces removed more than 100 bodies from al-Shifa Hospital.

Barsh said that Israeli forces removed 15 bodies from a mass grave, with a total of around 130 bodies taken from the hospital.  

The remaining functioning hospitals in Gaza are on the brink of collapse, even as more and more wounded and dead arrive on their doorsteps.

In the West Bank city of Nablus, at least five Palestinians were killed and several more sustained injuries when an Israeli air strike targeted a building at a refugee camp.

Wafa said the aerial strike targeted the local headquarters of the Palestinian Fatah resistance movement at Balata refugee camp early on Saturday.
Witnesses said the strike appeared to have come from a drone, though there was no immediate confirmation.

Local sources indicated that a number of young men were present in the building, including a number of those persecuted by the Israeli military.

The Palestine Red Crescent Society (PRCS) announced in a statement that its medics were dealing with five serious injuries from the attack, all of them men ranging from 19 to 25 years in age.

The Israeli newspaper Haaretz reported that four of those killed were affiliated with al-Aqsa Martyrs' Brigade, the armed wing of the Fatah faction.