RAMALLAH, West Bank ? Yasser Arafat’s nephew said Saturday his uncle might have died an “unnatural” death, a statement certain to renew speculation among Palestinians and in the rest of the Arab world where many already believe the late leader was poisoned despite Israel’s repeated and vehement denials.

Nasser al-Kidwa, who is also Palestinian envoy to the United nations, made the comments after he handed over the 558-page medical dossier to Palestinian officials in Ramallah. No diagnosis or reason has been given for Arafat’s death on Nov. 11 at a French hospital.

Al-Kidwa’s remarks could cause fresh tension between Israel and the Palestinians at a time when it appeared relations were improving. By providing fuel for rumors that Arafat was poisoned, his comments could also make it more difficult for a new Palestinian leadership to take control after presidential elections on Jan. 9.

But a decision on Saturday by Israel’s dovish Labor Party to join Prime Minister Ariel Sharon’s government could pave the way for him to implement his Gaza withdrawal plan and restart peace talks with the Palestinians.

After handing the 558-page medical dossier to interim Palestinian President Rauhi Fattouh, Al-Kidwa said French doctors could not rule out poisoning, but had not found traces in Arafat’s body of “any poison known to them.”

“Examinations of X-rays and all imaginable tests … are still with the same results, the inability of reaching a clear diagnosis,” Al-Kidwa said in English during a news conference.

“That is precisely the reason why suspicions are there, because without a reason you cannot escape the other possibility … that there is unnatural cause for the death,” he said.

French officials have said that judicial authorities would have opened an investigation had they suspected foul play.

Arafat, suffering from a mysterious illness, was urgently airlifted to the Percy Military Training Hospital in the southwestern Paris suburb of Clamart, on Oct. 29. His condition rapidly deteriorated and he fell into a coma.

A month after Arafat’s death at the age of 75 speculation still swirls about what killed him, with rumors ranging from cirrhosis of the liver to AIDS to poisoning.

Hani Masri, a commentator for the Palestinian newspaper Al-Ayyam, said many Palestinians already believe their leader was poisoned, and Israel had made clear on many occasions that it wanted to rid the region of Arafat.