Israeli and Palestinian pathologists disagreed Thursday on whether a blow to the body or a bad heart was the main cause of death of a Palestinian Cabinet minister who collapsed shortly after scuffling with Israeli troops during a West Bank protest.

Palestinian doctors said Ziad Abu Ein died from a blow, not natural causes. Israeli doctors said the 55-year-old died from a blockage of the coronary artery due to arterial bleeding that could have been caused by stress.

Abu Ein's death, along with the Palestinian autopsy findings, could further inflame tensions between Israel and the Palestinians.

Palestinian President Mahmoud Abbas has said Abu Ein was the victim of a crime and of a "barbaric act" and decreed three days of mourning.

Abu Ein's funeral procession began at Abbas' Ramallah headquarters Thursday. Several thousand mourners, including Abbas, gathered in the walled compound and said prayers over the minister's coffin, draped in a Palestinian flag. From there, the procession headed toward a nearby cemetery, with some in the crowd shooting in the air.

Anticipating Palestinian protests over Abu Ein's death, the Israeli military sent troop reinforcements to the West Bank. Earlier Thursday, several dozen Palestinian stone throwers clashed with Israeli troops in the West Bank city of Hebron.

Abu Ein died Wednesday, shortly after a West Bank confrontation between Palestinian protesters and Israeli soldiers that included pushing and shoving. At one point, a member of Israel's paramilitary border police grabbed Abu Ein by the throat and pushed him. Troops also fired tear gas during the confrontation.

Several minutes after the scuffle, Abu Ein collapsed to the ground, clutching his heart. He received first aid and was evacuated, but died en route to a hospital.

An autopsy was conducted later Wednesday by Palestinian, Jordanian and Israeli pathologists.

Palestinian pathologist Saber Aloul, citing preliminary findings, said Thursday that the "cause of death was a blow, and not natural causes."

He said that some of Abu Ein's front teeth were knocked out and dropped to the back of his mouth, and that regurgitated food entered the airway.

Palestinian Health Minister Jawad Awad said that "the results of the autopsy show that the ones who killed the martyr Ziad Abu Ein are the Israeli occupying forces."

Awad said two Jordanian pathologists also signed off on those findings, but that the Israeli doctors held off on a signature. The Israeli health ministry said the Israeli doctors didn't sign because it was a preliminary, not a final report.

Israeli pathologists Chen Kugel and Maya Furman said Abu Ein had a bad heart, including 80-percent blockage by plaque in the blood vessels of his heart, and that this "caused him to be more sensitive to stress."

They said in a statement that the coronary artery was blocked due to bleeding under a layer of atherosclerotic plaque, and that this bleeding could have been caused by stress. The doctors said light bleeding and localized pressure were found on his neck.

They said they wanted to see the medical treatment report before reaching further conclusions.

The Palestinian pathologist also cited bleeding in the coronary artery, saying it was a result of "anguish and stress," but added that "death was a result of injury."

Abu Ein's portfolio included organizing protests agEinst Israeli settlements and the West Bank separation barrier.

A member of Abbas' Fatah movement, Abu Ein had spent several years in Israeli prisons. He was arrested in the United States in 1979 and extradited to Israel two years later, according to a nephew, Baha Abu Ein. In Israel, he was sentenced to life in prison for being a member of a cell that planted a bomb that killed two Israelis. Abu Ein was released in a 1985 prisoner swap.

During the second Palestinian uprising in 2002, he spent a year in administrative detention without trial or charges.