A Russian report quoted by Palestinian investigators on Friday said there was insufficient evidence to support the theory that Yasser Arafat died in 2004 by polonium poisoning.
The findings were far weaker than those of a Swiss laboratory announced with fanfare on Wednesday by Arafat's widow and Qatar-based al-Jazeera television.
Palestinians remained unfazed by the results - which dampen but don't definitely disprove the possibility of death by poisoning - and officials continue to blame arch foe Israel.
Samples were extracted from Arafat's corpse last November by Swiss, French and Russian experts after an al-Jazeera documentary revealed unusually high amounts of the deadly Polonium isotope on his clothes.
"The outcome of the comprehensive report on the levels of Polonium-210 and the development of his illness does not give sufficient evidence to support the decision that Polonium-210 caused acute radiation syndrome leading to death," said Dr. Abdullah Bashir, quoting the conclusions of the Russian report.