UPDATE 1-UN rights chief 'horrified' by mass grave reports at Gaza hospitals

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GENEVA, April 23 (Reuters) - U.N. rights chief Volker Turk said on Tuesday that he was "horrified" by the destruction of the Nasser and Al Shifa medical facilities in Gaza and reports of mass graves containing hundreds of bodies there, according to a spokesperson.

Palestinian authorities reported finding bodies in mass graves at a hospital in Khan Younis this week after it was abandoned by Israeli troops. Bodies were also reported at the Al Shifa site following an Israeli special forces operation.

"We feel the need to raise the alarm because clearly there have been multiple bodies discovered," said Ravina Shamdasani, the spokesperson for the United Nations High Commissioner for Human Rights.

"Some of them had their hands tied, which of course indicates serious violations of international human rights law and international humanitarian law, and these need to be subjected to further investigations."

She added that the U.N. human rights office was working on corroborating Palestinian officials' reports that 283 bodies were found at Nasser and 30 at Al Shifa.

According to those reports, the bodies were buried beneath piles of waste and included women and older people. Turk, addressing a U.N. briefing via Shamdasani, also decried Israeli strikes on Gaza in recent days, which he said had killed mostly women and children.

He also repeated a warning against a full-scale incursion on Rafah, saying this could lead to "further atrocity crimes".

(Reporting by Emma Farge Editing by Miranda Murray)