Gaza's Civil Defence agency said Monday that health workers had uncovered around 200 bodies over the past three days of people killed and buried by Israeli forces at a hospital in Khan Yunis.
When asked for comment, the Israeli military said: "We will come back to you on the matter."
Mahmud Bassal, spokesman for Gaza's Civil Defence, told AFP that "civil defence crews are still recovering bodies from inside Nasser Medical Complex, and since Saturday bodies of nearly 200 martyrs have been retrieved".
Bassal said several of the recovered bodies had decomposed.
"There is difficulty in the process of identifying them but civil defence efforts are ongoing," he said.
On Sunday, Bassal told AFP that some of those killed had been tortured.
Ismail al-Thawabta, head of the Hamas government media office in the Palestinian territory, gave a higher figure of 283 bodies found at the hospital.
"We discovered mass graves inside Nasser Medical Complex" of people killed by "the occupation (Israeli) army", Thawabta told AFP.
"We demand an international investigation to closely examine these crimes against civilians, children, and women," he said.
Muhammad al-Mughayyir, a senior official at the civil defence agency, also confirmed the discovery of corpses at the facility and said the work to retrieve the remaining bodies would continue until Thursday.
Intense fighting raged in mid-February in the area of Nasser hospital and Israeli tanks and armoured vehicles surrounded it on March 26.
Hospitals in Gaza have not been spared in the Israeli assault against Hamas, which rules the Gaza Strip.
The Israeli military accuses Hamas of using hospitals and medical facilities as command centres and to hold hostages abducted in the October 7 attack.
Hamas denies the accusation.
The World Health Organization said on April 6 that the Palestinian territory's largest hospital, Al-Shifa in Gaza City, had been reduced to ashes by an Israeli siege last month, leaving an "empty shell" containing many bodies.
WHO staff who gained access to the devastated facility described horrifying scenes of bodies only partly buried, their limbs sticking out, and the stench of decomposition.
Israel is engaged in a sweeping military assault against Hamas militants in Gaza after the militant group launched an attack on southern Israeli communities on October 7.
The unprecedented attack resulted in the deaths of 1,170 people, according to an AFP tally based on official Israeli figures.
Some 250 people were abducted to Gaza during the attack, of whom 129 remain captive, including 34 the Israeli military says are dead.
Israel's retaliatory offensive has so far killed at least 34,151 people in the Gaza Strip, mostly women and children, according to the health ministry in the Hamas-run territory.