Hillary Clinton, the US secretary of state, has said Washington will wait for the results of any new investigation into Yasser Arafat's death and will not be responding to "rumours".
Speaking in Vietnam on Tuesday, Clinton said she would visit Israel next week to discuss a broad range of issues with Israeli leaders, including Middle East peace efforts.
Her arrival in the region comes as Mahmoud Abbas, the leader of the Palestinian Authority, has approved exhuming remains of the late Palestinian leader Yasser Arafat and wants an international probe of his predecessor's mysterious 2004 death.
Clinton said speculation will not help the process.
A nine-month investigation by Al Jazeera revealed earlier this month that Arafat was in good health until he fell ill abruptly and died in October 2004.
The report cited tests that revealed that Arafat's final personal belongings - his clothes, his toothbrush, even his iconic kaffiyeh - contained abnormal levels of polonium, a rare, highly radioactive element.
Those personal effects, which were analysed at the Institut de Radiophysique in Lausanne, Switzerland, were variously stained with Arafat's blood, sweat, saliva and urine.
The tests carried out on those samples suggested that there was a high level of polonium inside his body when he died.
"I can confirm to you that we measured an unexplained, elevated amount of unsupported polonium-210 in the belongings of Mr Arafat that contained stains of biological fluids," Dr Francois Bochud, the director of the institute, said.
The findings have led Suha Arafat, the widow of the former Palestinian leader, to ask the Palestinian Authority to exhume her late husband's body from its grave in Ramallah.
If tests show that Arafat's bones contain high levels of polonium, it would be more conclusive proof that he was poisoned, doctors say.
"I know the Palestinian Authority has been trying to discover what Yasser died from," Suha Arafat said in an interview. "And now we are helping them. We have very substantial, very important results."
The institute studied Arafat's personal effects, which his widow provided to Al Jazeera, the first time they had been examined by a laboratory.
Doctors did not find any traces of common heavy metals or conventional poisons, so they turned their attention to more obscure elements, including polonium.
Source: Al Jazeera and agencies