A Palestinian protester throws a stone during clashes with Israeli soldiers and border policemen in the West Bank city of Hebron on Feb. 24, 2013. The death in an Israeli jail of a Palestinian detainee on Saturday and an on-going hunger strike by four inmates have fueled tensions in the West Bank. (AMMAR AWAD/REUTERS)

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.”

Qaraqe told a news conference that the findings included severe bruises on Jaradat’s back and chest, two broken ribs, and injuries showing “evidence of severe torture” in shoulder and chest muscles.

The Israeli health ministry said “no signs of external trauma” were found, except for a small chest scrape and marks left by resuscitation efforts, which also could have caused the broken ribs. Internal bleeding was found in shoulder and chest muscles and in the prisoner’s elbows.

“These initial findings cannot determine the cause of death,” the ministry said, adding that before receiving results of microscopic and toxicological tests “the cause of death cannot be linked to the findings of the autopsy.”

Kamil Sabbagh, a lawyer who met Jaradat at a military court hearing Thursday, said he bore no signs of violence, but complained of back pains and other aches because of prolonged sitting in an interrogation chair.

Jaradat was in visible “psychological distress,” fearing his return to an isolation cell, Sabbagh said, adding that at his request the judge ordered that Jaradat be given medical care.

The Shin Bet said Jaradat was known to suffer from chronic back pain and was examined several times by a doctor during the interrogation. The questioning proceeded when no medical problems were found, according to the agency’s statement.

News of Jaradat’s death set off clashes between stone-throwing youths and troops near his home village of Sa’ir, north of Hebron, inside the city and in neighboring areas, spreading to other locations in the West Bank, according to reports by the military and Palestinians.

In Hebron, protesters set up barricades of burning tires and hurled rocks and molotov cocktails at soldiers, who responded with stun grenades, tear gas and rubber-coated bullets, the army said. One Palestinian was wounded by live fire at al-Aroub refugee camp south of Bethlehem, and two soldiers were lightly injured by stones in other locations, the army said.

Palestinian Authority Prime Minister Salam Fayyad issued a statement expressing “deep sorrow and shock” at Jaradat’s death, and said it was imperative “to promptly disclose the true reasons that led to this martyrdom.”

Qaraqe demanded a “neutral international inquiry” into the death.

“If President Obama wants to visit the region peacefully, he should exert pressure on Israel to release the prisoners — especially the ones who are on hunger strike — or else he will visit while Palestine is on fire,” Qaraqe said at a news conference.

Two of the hunger strikers have been detained without charges for three months. Two others were rearrested months after their release in the 2011 prisoner exchange that freed Gilad Shalit, the Israeli soldier held captive in Gaza by the militant Islamist group Hamas. Held on the basis of secret evidence, both of the rearrested prisoners face a possible return to jail for the duration of their original sentences.

One of the rearrested prisoners, Samer Issawi, has been on an intermittent hunger strike for more than 200 days, according to human rights groups monitoring his condition. Mohammad Barakeh, an Israeli Arab parliament member who visited Issawi in a prison medical center, told Israel Radio on Sunday that Issawi was “skin and bones” and had declared that he would stop drinking water.