The Palestinian prisoner who died in Megiddo Prison on Saturday did not expire from a heart attack, as Israeli officials previously claimed, but from torture, says a Palestinian doctor who was present for the autopsy performed by an Israeli doctor Sunday.

Saber Aloul, chief pathologist of the Palestinian Authority, who attended the autopsy in Israel, said marks on Arafat Jaradat's body showed he had been tortured during his interrogation.

The autopsy, performed at the National Institute of Forensic Medicine, listed no

cause of death.

The Shin Bet security service denied Aloul was tortured. A Health Ministry spokesperson said no exterior signs of injuries were discovered during the medical examination, apart from resuscitation bruises and a small abrasion on the right side of Jaradat's chest.

The examination was conducted by the institute's chief pathologist, Yehuda Hiss, in the presence of Aloul and the head of the Health Ministry's medical administration, Prof. Arnon Afek.

Prior to the autopsy, Israeli officials had said Jaradat likely died of cardiac arrest, while Palestinians believed he died as a result of torture.

No sign of heart failure was found during the examination, nor was any other sign of illness, according to Aloul and Israeli officials.

Pathologists are now awaiting the results of microscopic and toxicology tests, which might take days or even weeks to receive.

Jaradat's death sparked clashes throughout the West Bank Sunday and Palestinians called for an international investigation of Israel's treatment of detained Palestinians.

In all, Israel holds close to 4,600 Palestinians on a range of charges, from throwing stones at Israelis to involvement in deadly shooting and bombing attacks. Of the detainees, 159 are being held without charges or trial in administrative detention.

According to the Shin Bet, Jaradat was arrested last Monday, after residents of his village said he was involved in a rock-throwing attack that injured an Israeli. Jaradat admitted to the charge, as well as to another West Bank rock-throwing incident last year, the Shin Bet said.

The Shin Bet said that during interrogation he was examined several times by a doctor who detected no health problems. On Saturday, he was in his cell and

felt unwell after lunch, the security service said in a statement. "Rescue services and a doctor were alerted and treated him. They didn't succeed in saving his life," the statement said.

A Shin Bet spokesman, speaking on condition of anonymity in line with protocol, said Jaradat was not beaten during his interrogation, nor was he subjected to any treatment that could have affected his health. Jaradat was not on a hunger strike, said Sivan Weizman of the Israel Prison Service. Prior to the autopsy, Weizman said Jaradat had died of an apparent heart attack.

Jaradat's attorney, Kamil Sabbagh, said his client told an Israeli military judge during a hearing on Thursday that he was being forced to sit for long periods during interrogation. He also complained of back pain and seemed terrified to return to the Shin Bet lockup, but did not have any apparent signs of physical abuse, Sabbagh said.

After the court hearing, the judge ordered Jaradat to be examined by a prison doctor.

Jaradat, a father of a 4-year-old daughter and 2-year-old son, worked as a gas station attendant. His wife, Dalal, is pregnant, relatives said. Issa Karake, a Palestinian official who handles prisoner issues, said he holds Israel responsible for Jaradat's death, alleging ill-treatment and medical negligence. Karake called for an independent international investigation of Israel's treatment of Palestinian detainees.

The human rights group B'Tselem also demanded an investigation, including how Jaradat was questioned.

The agency routinely holds detainees in isolation for extended periods during interrogation, keeping them in cells that are lit around the clock and denying them access to lawyers, said Sarit Michaeli, a spokeswoman for the group.

She said that physical mistreatment of detainees had dropped sharply in recent years, but has not disappeared, according to affidavits by released prisoners. She also said detainees have filed some 700 complaints about mistreatment by Shin Bet agents during the past decade, but that none has led to a criminal investigation.