JERUSALEM -- The discovery of traces of a radioactive agent on clothing reportedly worn by Yasser Arafat in his final days reignited a cauldron of conspiracy theories Wednesday about the mysterious death of the longtime Palestinian leader.

Mr. Arafat's widow, who ordered the tests by a Swiss lab, called for her husband's body to be exhumed, and Mr. Arafat's successor gave tentative approval for an autopsy.

Saeb Erekat, a close aide of the president of the Palestinian Authority, Mahmoud Abbas, said that once the religious authorities and Mr. Arafat's relatives had given the go-ahead, an exhumation could take place "in the coming days."

Then, Mr. Erekat said, the Palestinians would seek an international inquiry into Mr. Arafat's death similar to the United Nations-backed tribunal that investigated the assassination of Rafik Hariri, a former Lebanese prime minister.

But experts warned that even after the detection of polonium-210, getting answers on the cause of death will be tough.

Mr. Arafat was 75 when he died Nov. 11, 2004, in a French military hospital. He had been airlifted to the facility just weeks earlier with a mysterious illness, after being confined by Israel for three years to his West Bank headquarters.

At the time, French doctors said Mr. Arafat died of a massive stroke. According to French medical records, he had suffered inflammation, jaundice, and a blood condition known as disseminated intravascular coagulation.

But the records were inconclusive about what brought about the DIC, which has numerous causes including infections, colitis and liver disease. Outside experts who reviewed the records were also unable to pinpoint the underlying cause.

The uncertainty sparked speculation about the cause of death, including the possibility of AIDS or poisoning. 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.

"Ultimately all the documents surrounding Arafat's death are in Palestinian hands," a senior Israeli official said, speaking on condition of anonymity because he was not authorized to speak publicly about the issue. "Instead of spreading conspiracy theories, the Palestinians could just make the documents public."

That debate was reignited after a Swiss lab said Wednesday it had discovered traces of polonium-210 in clothing and other belongings provided by Mr. Arafat's wife, Suha. She told the lab that Mr. Arafat had used the items in his final days.

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.

Francois Bochud, who heads the Institute of Radiation Physics in Lausanne, Switzerland, said Wednesday that his lab had discovered "very small" quantities of polonium-210, which is naturally present in the environment. But levels found in blood and urine samples taken from the clothing were well above normal.

Mr. Bochud said an "elevated" level of more than 100 millibecquerel, a measurement of radioactivity, was found on Mr. Arafat's belongings. That's compared with levels of some 10 millibecquerel in some control samples. Mr. Bochud said the discovery did not provide proof that Mr. Arafat had been poisoned.

That would require further testing.

First Published July 5, 2012, 4:52 a.m.