Palestinian Authority President Mahmoud Abbas on Tuesday called for an international investigation into the death of Arafat Jaradat, a Palestinian prisoner who died while under Israeli detention last week.

A Palestinian pathologist who attended Jaradat’s autopsy determined on Sunday that the man had been tortured to death and had not died of a heart attack, as Israeli authorities maintain.

Saeb Erekat, the PA’s chief negotiator, passed Abbas’s request on to Robert Serry, the special UN envoy to the region, and asked him to forward it to Secretary General Ban Ki-moon, Israel Radio reported. Serry called on Monday night for an “independent and transparent” investigation into the inmate’s death.

Serry’s demand was echoed Tuesday by Under Secretary-General for Political Affairs Jeffrey Feltman at a UN Security Council briefing.

Feltman urged a prompt investigation and called for the results to be “made public as soon as possible.”

“The United Nations underscores the importance of restoring and maintaining calm,” Feltman told the Security Council. He expressed “particular concern” over “the deteriorating health of four prisoners who have engaged in extended hunger strike” in Israeli jails – a strike that had already rallied some supporters in the West Bank to demonstrate.

Jaradat’s family members have claimed they saw bloodstains on his body after they went to identify his remains at Israel’s main forensics institute on Sunday morning. They said they didn’t believe that he had died of natural causes.

Israel’s Justice Ministry issued a statement saying no visible signs of violence were detected on Jaradat’s body, aside from those made by resuscitation efforts and a small graze on his chest.

“Two internal bleeds were detected, one on the shoulder and one on the right side of the chest. Two ribs were broken, which may indicate resuscitation attempts. The initial findings cannot determine the cause of death,” read the statement. “At this stage, until microscopic and toxicology reports are in, the cause of death cannot be tied to the autopsy findings.”

The autopsy’s official findings will be forwarded in two weeks to the PA and to Israel’s international criminal investigation unit. After the inspection, Jaradat’s body was handed over to his family for burial.

Palestinians called for an international investigation of Israel’s treatment of detained Palestinians, after Jaradat’s death and ongoing hunger strikes by four other inmates sparked a week of West Bank protests.

Stuart Winer and the Associated Press contributed to this report.