Swiss scientists have given details about the traces of a radioactive substance found on personal items belonging to Yasser Arafat, adding to claims that the late Palestinian president was poisoned by Israel.

The discovery of polonium-210 on Arafat's effects was first made public last year. His body was exhumed from its mausoleum in the West Bank city of Ramallah last November for tests by Swiss, French and Russian scientists, but no results have been officially disclosed.

In a paper in the medical journal the Lancet, toxicologists said they had examined 38 items belonging to Arafat, including underwear and a toothbrush, and compared them with a control group of 37 items of his that had been in storage for some time before his death in 2004.

They found traces of the substance that "support the possibility of Arafat's poisoning with polonium-210", the scientists reported adding: "Although the absence of myelosuppression [bone marrow deficiency] and hair loss does not favour acute radiation syndrome, symptoms of nausea, vomiting, fatigue, diarrhoea, and anorexia, followed by hepatic and renal failures, might suggest radioactive poisoning."

However, a Russian official said on Tuesday that tests on Arafat's remains had produced no signs of polonium-210. "He could not have died of polonium poisoning – the Russian experts found no traces of this substance," Vladimir Uiba, head of Russia's Federal Medical-Biological Agency, told the Interfax news agency on Tuesday.

Arafat died at the age of 75 in a hospital near Paris in November 2004 after falling ill while holed up under Israeli military siege at his presidential compound, the Muqata, in Ramallah. Doctors could not conclusively identify the cause of death. Claims that he had been poisoned by Israel swiftly took hold among Palestinians, who revered Arafat as a resistance leader.

No postmortem was conducted on his body, but after al-Jazeera aired the polonium-210 suspicions last year, the Palestinian Authority agreed to a request by Arafat's widow, Suha, and French judicial investigators to exhume his body for further tests.

The Swiss scientists said: "An autopsy would have been useful in this case because although potential polonium poisoning might not have been identified during that procedure, body samples could have been kept and tested afterwards."

Polonium-210 was used to kill Alexander Litvinenko, a former Russian KGB agent, who died in London in 2006.