"We have completed all the studies," Vladimir Uiba, head of Russia's Federal Medical-Biological Agency (FMBA), told a news conference.

"The person died a natural death and not from radiation," he said.

The Palestinians have long suspected that Arafat was poisoned, with some pointing the finger directly at Israel.

A Palestinian envoy said the Palestinian authorities will press on with a probe into the 2004 death of Arafat.

“I can only say that there is already a decision to continue (the investigation)," Faed Mustafa, the Palestinian ambassador to Russia, told the state RIA Novosti news agency.

"We respect their position, we highly value their work but there is a decision to continue work," he said. "We need a result, a final and concrete result to take the issue off the table."

Arafat died in France on November 11, 2004 at the age of 75, but doctors were unable to specify the cause of death. No autopsy was carried out at the time, in line with his widow's request.

A decision to ask the UN General Assembly to establish an international commission to investigate the circumstances of Arafat's death was taken at an Arab League meeting in Cairo on Saturday.

His remains were exhumed in November 2012, partly to investigate whether he had been poisoned with radioactive polonium, a suspicion that grew after the substance was used to assassinate Russian ex-spy and Kremlin critic Alexander Litvinenko in 2006.

Some 60 samples were taken and divided between Swiss and Russian investigators as well as a French team carrying out a probe.

The Russian agency in October doubted a report published in The Lancet, saying that Swiss radiation experts had found traces of polonium on Arafat's clothing.

The Swiss team said at the time its findings "support the possibility" the veteran Palestinian leader was poisoned.

SHI/SHI