The United Nations called for “a clear, transparent and credible investigation” of mass graves uncovered at two major hospitals in Gaza that were raided by Israeli troops, Al Jazeera reports.

Ravina Shamdasani, a spokeswoman with the UN’s human rights office, demanded independent and transparent investigations into the deaths, saying “given the prevailing climate of impunity, this should include international investigators”.

Credible investigators must have access to the sites, UN spokesman Stephane Dujarric told reporters, adding more journalists need to be able to work safely in Gaza to report the facts.

Earlier, UN human rights chief Volker Turk said he is “horrified” by the destruction of the Al-Shifa Hospital in Gaza City and Nasser Hospital in the southern city of Khan Younis, and reported mass graves in and around the facilities after the Israelis left.