A Palestinian investigation committee on Friday accused Israel of being behind the " assassination" of former Palestinian leader Yasser Arafat.

Calling Arafat's death "unnatural," Tawfiq al-Tirawi, head of the committee, told a news conference in the West Bank city of Ramallah that "We say that Israel is the first, basic and sole suspect accused in the assassination of Arafat."

"What the (Swiss and Russian) experts have concluded gets us closer to the truth, but it's not the end of the way," said al- Tirawi.

On Thursday, Swiss scientists who examined Arafat's corpse said that high levels of the radioactive substance polonium-210 were found in Arafat's remains and the tomb's soil, but poisoning remains a hypothesis, not a certainty.

Arafat died from an unknown diseases while receiving treatment at a French hospital near Paris in 2004. Palestinian officials hinted that Israel was behind the death.