Forensic tests on the body of the late Palestinian leader Yasser Arafat are reported to show unexpectedly high levels of radioactive polonium.
Mr Arafat's body was exhumed last year amid claims he had been poisoned.
A Swiss forensic report says tests on the body showed "unexpected high activity" of polonium, which "moderately" supported the poisoning theory.
Mr Arafat's widow says her late husband had 18 times more polonium in his system than would be normal.
The official report says, in all probability, there was some kind of toxicity in Mr Arafat's system, the BBC reports.
The results were based on limited samples and the scientists say that prevented them reaching a more definitive conclusion.
They were also hampered by the amount of time that has passed since Mr Arafat's death in 2004.
Many Palestinians believe Israel was behind the death but the Israelis categorically deny that.