The head of the Palestinian commission investigating Arafat's 2004 death told reporters on Friday that Israel was the "only suspect," calling the late president's passing an "assassination."

"He did not die of old age and not of an illness," committee head Tawfiq Tirawi said at a news conference in the West Bank city of Ramallah.

"We say that Israel is the prime and only suspect in the case of Yasser Arafat's assassination, and we will continue to carry out a thorough investigation to find out and confirm all the details and all elements of the case," said Tirawi.

But Israeli officials have strongly denied the allegations, saying that they "couldn't be bothered" to kill Arafat.

"If anyone remembers the political reality at the time, Arafat was completely isolated," said Israeli Foreign Ministry official Paul Hirschson. "His own people were barely speaking to him. There's no logical reason for Israel to have wanted to do something like this."

Poisoning theory 'reasonably supported'

On Thursday, Swiss scientists said test resultsfrom Arafat's remains showed elevated levels of polonium-210 and lead, which could not have occurred naturally.

The forensic and radiological team from the Lausanne University Hospital Center said that their results support the theory that Arafat was poisoned. But the team emphasized that they could not conclude with complete certainty that he did in fact die from polonium poisoning.

"Our results reasonably support the poisoning theory," said Francois Bochud, director of Switzerland's Institute of Radiation Physics, at a press conference on Thursday.

"Can we say with certitude that polonium was the cause of death of President Arafat?" Bochud said. "Unfortunately for those of you who want a clearly defined answer, the answer is no. That is to say our study did not permit us to demonstrate categorically the hypothesis of poisoning by polonium"

Meanwhile, Patrice Mangin, director of Lausanne University Hospital's forensics center, said the investigative team had ruled out explanations like accidental poisoning.

"I think we can eliminate this possibility because, as you can imagine, you cannot find polonium everywhere," Mangin told the Associated Press. "It's a very rare toxic substance."

Arafat died at a French military hospital in 2004. He had suddenly fallen ill after eating a meal, suffering from vomiting and stomach pains. Although the official cause of death was a massive stroke, French doctors at the time said they were unable to determine the origin of his illness.

The investigation into Arafat's death was opened after reporting by Qatar-based broadcaster Al Jazeera revealed that Arafat's clothes were tainted with traces of polonium.

slk/dr (AP, AFP, dpa, Reuters)