Over 400 bodies have now been recovered from mass graves in and around a major hospital in Gaza's Khan Younis, relief workers have said.
Three mass graves containing hundreds of bodies, mostly of women and children, were discovered at Nasser Hospital, aid groups told Sky News Arabia.
This comes after Gaza's civil defence said on Sunday that health workers had uncovered bodies of people killed and buried by Israeli forces at Nasser Hospital during their raid.
The mass graves were discovered weeks after Israeli forces ended a three-month occupation of Khan Younis, where they repeatedly attacked the Nasser Hospital and reportedly carried out executions on the spot.
The hospital was considered one of Gaza’s biggest but by February was barely functioning after Israeli forces launched a deadly raid on it, where hundreds were detained and medical staff beaten.
According to Sky News Arabia, the death toll could rise with "dozens" of additional graves yet to be evaluated in Khan Younis.
Abdullah Obaid, a local aid worker, told the news outlet that the largest graves were found nearest to Nasser Hospital and confirmed they contained the bodies of civilians who were killed during the Israeli raids.
He emphasised that "the smell of decomposing bodies is widespread in every location within the city".
"When we entered the city, we did not find any living people there, and we could smell the scent of death strongly," Obaid told Sky News Arabia.
"There are no signs that indicate to us that this area contains a mass grave, but we target any area that we feel has piles of sand or dirt or where the ground has been razed. Until this moment, we have found 3 mass graves, each grave containing hundreds of dead people, most of whom are women and children.
"We are certain that there are dozens of graves and we are searching for them because we have lists of more than two thousand missing persons" he explained.
More bodies were also uncovered at Gaza City’s Al-Shifa Hospital after Israeli forces besieged the facility last month, reducing its buildings to ashes.
Palestinian journalists say the southern city is the enclave's "most destroyed area".
Local media added that the carnage has completely dismantled access to communications, drinking water, sewage systems and electricity.
Calls for investigations
The UN has since called for "a clear, transparent and credible investigation", as UN human rights chief Volker Türk said he was "horrified" by the destruction of the Shifa medical centre and Nasser Hospital.
He called for independent and transparent investigations into the killings, saying that "given the prevailing climate of impunity, this should include international investigators".
"Hospitals are entitled to very special protection under international humanitarian law," Türk said. "And the intentional killing of civilians, detainees and others who are ‘hors de combat’ (incapable of engaging in combat) is a war crime."
US State Department spokesman Vedant Patel on Tuesday called the reports of mass graves at the hospitals "incredibly troubling" and said US officials have asked the Israeli government for information.
Israel's army has since rejected the claims that its troops buried hundreds of Palestinian bodies at a Gaza hospital as "baseless", saying corpses had been examined in a search for hostages.
However, it acknowledged that troops had examined corpses buried at the facility.
South Africa has also for an immediate probe and argued that Israel has continually disregarded the UN’s International Court of Justice rulings.
The ICJ preliminary ruling in South Africa's case ordered Israel to do all it can to prevent death, destruction and any acts of genocide against Palestinians in the territory.
It stopped short of ordering a ceasefire but ruled Israel must urgently get basic humanitarian aid to Gaza and submit a report on steps taken to abide by the ruling within a month.
Since the ruling, Israeli forces have intensified its air and ground military offensive in Gaza with at least 34,262 people killed in the enclave in more than six months of war, according to Gaza’s health ministry.
The tally includes at least 79 killings in the past 24 hours, the ministry statement said, adding that 77,229 people have been wounded in the Gaza Strip.
Multiple press agencies have also contributed to this report.