The United Nations called for a "a clear, transparent and credible investigation" of mass graves discovered at the al-Shifa Hospital in Gaza City and the Nasser Hospital in Khan Younis, both of which were recently raided by Israeli troops. 

UN spokesperson Stephane Dujarric told reporters that credible investigators and more journalists must have safe access to the sites to conduct factual assessments of the situation.

However, he added, for the UN to conduct the investigation, one of its major bodies would have to authorize it. 

"I think it's not for anyone to prejudge the results or who would do it," he told reporters. "I think it needs to be an investigation where there is access and there is credibility."

Dujarric further stated that the discovery of the graves was "another reason why we need a cease-fire, why we need to see an end to this conflict, why we need to see greater access for humanitarians, for humanitarian goods, greater protection for hospitals" and the release of Israeli hostages

Earlier on Tuesday (Apr. 23), UN human rights chief Volker Türk also called for an independent investigation of the incident, saying that he was "horrified" by the destruction of the two hospitals after the Israeli Defense Forces (IDF) and the Shin Bet security service withdrew from both of them and the south of Gaza earlier this month.

He also expressed distress over the reported discovery of mass graves in and around both facilities in the aftermath of the raids.

"Given the prevailing climate of impunity, this should include international investigators," he said in a statement.

"Hospitals are entitled to very special protection under international humanitarian law. 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 spokesperson Vedant Patel also called the reports of mass graves at the hospitals "incredibly troubling" and said that officials in Washington have asked the Israeli government for information.

On the other hand, Israeli military officials said that its forces exhumed bodies that Palestinians had buried earlier as part of its search for the remains of hostages captured by Hamas during its Oct. 7 attack that triggered the war.

They added that the bodies were examined respectfully, and those not belonging to Israeli hostages were returned to their places.

IDF officials also said that it killed or detained hundreds of militants who had taken shelter inside the two hospital complexes, claims that could not be identified, the Associated Press reported.

Meanwhile, International Criminal Court chief prosecutor Karim Khan said that a probe by the court into possible crimes by both Hamas militants and Israeli soldiers is a "priority" for his office after he visited Israel and the West Bank in December.