MOSCOW — A Russian probe into the death of Palestinian leader Yasser Arafat has found no trace of radioactive poisoning, the chief of the government agency that conducted the study said today.

Vladimir Uiba, the head of the Federal Medical and Biological Agency, said the agency had no plans to conduct further tests.

“It was a natural death; there was no impact of radiation,” Uiba said, according to Russian news agencies.

Teams of scientists from France, Switzerland and Russia were asked to determine whether polonium, a rare and extremely lethal substance, played a role in Arafat’s death in a French military hospital in 2004. Palestinians have long suspected Israel of poisoning him, which Israel denies. Russia, meanwhile, has had close ties with Palestinian authorities since Soviet times when Moscow supported their struggle.

After a 2012 report which said traces of radioactive polonium were found on Arafat’s clothing, his widow Suha Arafat asked for an investigation into whether he was murdered.

As part of that probe, French investigators had Arafat’s remains exhumed and ordered a series of tests on them.

Suha Arafat said the French experts found traces of polonium but determined it was “of natural environmental origin.”

Polonium occurs naturally in very low concentrations in the Earth’s crust and also is produced artificially in nuclear reactors.

Swiss scientists, meanwhile, said they found elevated traces of polonium-210 and lead, and that the time frame of Arafat’s illness and death was consistent with poisoning from ingesting polonium.

Palestinian Ambassador to Russia, Fayed Mustafa, said today the Palestinian authorities respect the Russian experts’ conclusions but consider it necessary to continue research into Arafat’s death.

Arafat died Nov. 11, 2004, a month after falling ill at his West Bank headquarters. At the time, French doctors said he died of a stroke and had a blood-clotting problem, but records were inconclusive about what caused that condition.