JERUSALEM – The death of a Palestinian prisoner under Israeli interrogation after a week of demonstrations for the release of four other inmates on hunger strikes triggered fresh clashes Sunday and heightened concerns in Israel about a swelling wave of unrest in the West Bank.The Palestinian Authority said that the results of an Israeli autopsy attended by the chief Palestinian forensic pathologist showed that the prisoner had been tortured. But Israel’s health ministry said the preliminary findings could not determine the cause of death, though they did not support initial Israeli assertions that the prisoner had died of cardiac arrest. With Israeli media raising the specter of a third Palestinian uprising, Prime Minister Benjamin Netanyahu dispatched an envoy to demand that the Palestinian Authority restore calm, while ordering the release of frozen tax funds collected last month for the Palestinians, a senior Israeli official said.Israel had suspended the tax transfers, which make up two-thirds of the Palestinian Authority’s domestic revenue, in response to the Palestinian’s successful bid in November for recognition as a non-member state in the United Nations.The rising tensions in the West Bank come weeks before a planned visit by President Obama, amid a protracted stalemate in peace efforts and growing economic hardship as the cash-strapped Palestinian Authority struggles to pay more than 150,000 employees. Following days in which hundreds of Palestinian demonstrators confronted Israeli forces in the West Bank and Jerusalem, Saturday’s death of the prisoner, Arafat Jaradat, 30, threatened to ignite wider protests, and Israeli troops were put on heightened alert.Crowds of stone-throwing youths confronted security forces in several locations in the West Bank on Sunday. The 4,600 Palestinian prisoners in Israeli jails refused meals to protest the death of their colleague, according to a spokeswoman for the Israeli prisons service.Israel’s Shin Bet security agency said in a statement Saturday that Jaradat, who relatives said had two children and worked at his father’s gas station, had confessed to involvement in a stone-throwing incident in which an Israeli was injured in November. The prisoner died five days after his arrest during a break between interrogations at Megiddo prison, the statement said.The statement did not give a cause of death and said that police had opened an investigation, though a spokeswoman for Israel’s prisons service said initial findings pointed to cardiac arrest.Sunday’s autopsy at Israel’s National Institute of Forensic Medicine found no evidence of heart disease, according to both Israeli and Palestinian reports of the findings. But the other results were disputed. Relaying a report from Saber al-Aloul, director of the Palestinian Forensic Medicine Institute, who attended the autopsy, Palestinian Minister of Detainees Affairs Issa Qaraqe said it showed that Jaradat had "been subjected to severe torture that led to his immediate death.”