Nine people have been killed and scores injured by blasts at a UN compound housing displaced civilians in Khan Younis, in southern Gaza, the UN’s agency for Palestinian refugee says.
UNRWA said two tank shells hit the training college in the west of the city, where 800 people were sheltering.
Israel has not commented specifically on the blasts but said its forces were operating in the surrounding area.
Its troops have encircled the city and ordered people still there to leave.
UNRWA’s Gaza director, Thomas White, said on X, formerly Twitter, that its Khan Younis Training Centre had been hit during fighting and added that there were “mass casualties”.
He told CNN that the blasts struck a carpentry building after two days of fighting around the centre, when UN staff had been unable to get there.
“We are in constant contact with the Israeli army, who have been giving assurances that people in protected facilities… are safe,” he added.
“The reality is that lives have been taken in and around these facilities in the last couple of days.”
It comes as fierce fighting rages in southern Gaza, including in the densely populated refugee camp within Khan Younis, which is in close proximity to the UNWRA training centre.
The IDF said Israeli forces were “located around the camp, in the western part, and have begun to operate within it”.
It said they were part of a “divisional manoeuvre” around western Khan Younis to dismantle “Hamas’ military framework”.
“The manoeuvre will continue against military targets that are in the area, outposts, infrastructure, and command and control centres,” it said, adding that Hamas “exploited” the densely populated area, as well as its shelters and hospitals.
The Hamas-run Gaza health ministry said more than 200 Palestinians had been killed in the past 24 hours, amid some of the heaviest fighting yet seen in the Israeli campaign to destroy Hamas.
Israel launched its invasion of Gaza days after Hamas killed more than 1,300 people and took more than 250 hostages in its 7 October attacks inside Israel.
Heavy fighting was meanwhile reported close to hospitals in Khan Younis, including Nasser and Al-Amal, with reports of Palestinians trying to flee, said the UN humanitarian agency OCHA.
“No-one can enter or exit [Nasser Hospital] due to ongoing bombardments,” OCHA said, citing medics who also reported that staff were digging graves on the grounds of the facility “due to the large numbers of fatalities anticipated”.
On Tuesday, Israel’s military had given fresh evacuation orders for part of Khan Younis which OCHA said were home to 500,000 people – four-fifths of them refugees from other parts of Gaza.
There have been repeated international calls for Israel to cease its months-long bombardment of the enclave.
Israeli Prime Minister, Benjamin Netanyahu, has reiterated that Israel will continue fighting in Gaza until Hamas is toppled and the remaining Israeli hostages taken by Hamas on 7 October are brought home.
Civilian with white flag shot dead
On Monday, a cameraman for the UK’s ITV News filmed a Palestinian civilian being shot dead on a street about 1.7km (1 mile) south of the UNRWA shelter.
Five men are seen walking towards the combat zone holding a white flag, before there is a burst of gunfire and one of them falls to the ground. It was not clear who opened fire.
Prime Minister Rishi Sunak was asked in the British parliament on Tuesday whether such pictures would prompt him to push for a ceasefire in Gaza.
He replied: “No-one wants to see this conflict go on for a moment longer than is necessary and we do want to see an immediate and sustained humanitarian pause.”
On Tuesday morning, a senior Palestinian official familiar with ongoing talks in Cairo told the BBC that Egyptian mediators had made a new proposal to Hamas to stop the war.
According to the official, a new five-stage proposal would start with a humanitarian truce in exchange for the release of Israeli civilians held hostage by Hamas.
A main sticking point is said to be at which point Israeli troops would withdraw from Gaza.
Abdul Fattah al-Sisi, Egypt’s president, has meanwhile accused Israel of deliberately holding up aid deliveries at the Rafah border crossing into Gaza to increase pressure on Hamas.
He told a gathering of military and state officials that lengthy Israeli inspections meant only a third of the usual number of aid trucks entered the territory.
Israel insists the inspections are necessary to ensure no weapons reach Hamas.