Arafat died at the age of 75 on Nov. 11, 2004, just weeks after falling ill. There were conspiracy theories that he had been poisoned.
A Swiss lab says it found elevated levels of the radioactive isotope polonium on his belongings. Polonium-210 is best known for causing the death of Alexander Litvinenko, a one-time KGB agent turned critic of the Russian government, in London in 2006.
French doctors at the time said Arafat died of a massive brain hemorrhage. According to French medical records, he had suffered inflammation, jaundice and a blood condition known as disseminated intravascular coagulation, or DIC.
Arafat's widow had declined an autopsy, but now she is calling for her husband's body to be exhumed, and Arafat's successor gave tentative approval for an autopsy.
Many in the Arab world believe he was killed by Israel, which held him responsible for the bloody Palestinian uprising of the early 2000s. Israeli officials have repeatedly denied foul play, and they dismissed the latest theories as nonsense.
"Making up conspiracy theories based on pretend evidence is so ludicrous that it befits the comedy channel and not a news channel," said Foreign Ministry spokesman Yigal Palmor. "If there is anything suspicious about his death, then the French doctors would have known and said something."
The Associated Press contributed to this report.