PARIS - Extensive reports by French scientists into Palestinian leader Yasir Arafat's death have ruled out poisoning by radioactive polonium, his widow said Tuesday. The results contradict earlier findings by a Swiss lab and mean it's still unclear how Arafat died nine years ago.

Scientists from several countries have tried to determine whether polonium played a role in Arafat's death at a French military hospital in 2004. Palestinians have long suspected Israel of poisoning him, which Israel denies.

After a 2012 report that traces of radioactive polonium were found on Arafat's clothing, his widow, Suha, filed a legal complaint in France seeking an investigation into whether he was murdered.

As part of that investigation, French investigators sought the exhumation of Arafat's remains and ordered genetic, toxicology, medical, anatomical, and radiation tests. Suha Arafat and her lawyers were notified Tuesday of the results.

She told reporters in Paris that the results excluded the possibility of poisoning by polonium, a rare and extremely lethal substance. She said the French investigators did not rule out the possibility that he died of natural causes.

This is the latest in a string of recent expert reports on Arafat's death: A Swiss lab said that Arafat was probably poisoned by polonium. A Russian report given to Palestinian officials was inconclusive. But both reports said his death was caused as a result of toxic substances, not natural causes.

Suha Arafat said she was "upset by these contradictions by the best European experts on the matter."

The French experts found traces of polonium but came to "diametrically opposed conclusions" from the Swiss about where it came from, Suha Arafat's lawyer Pierre-Olivier Sur said.

Arafat died Nov. 11, 2004, at a French military hospital, a month after falling ill at his West Bank headquarters. At the time, French doctors said he died of a stroke and had a blood-clotting problem, but records were inconclusive about what caused that condition.