Arafat fell ill in October 2004, displaying symptoms of acute gastroenteritis with diarrhoea and vomiting. At first Palestinian officials said he was suffering from influenza.
He was flown to Paris in a French government plane but fell into a coma shortly after his arrival at the Percy military hospital in the suburb of Clamart, where he died on 11th November.
The official cause of death was a massive stroke but French doctors said at the time they were unable to determine the origin of his illness and no autopsy was carried out.
Polonium- 210 was responsible for the death of defecting Russian spy Alexander Litvinenko in 2006 after it was slipped into a cup of tea in a London hotel. From his deathbed, Litvinenko accused Russian President Vladimir Putin of ordering his murder.
Professor David Barclay, a British forensic scientist retained by Al Jazeera to interpret the results of the Swiss tests, said the findings from Arafat's body confirmed the earlier results from traces of bodily fluids on his underwear, toothbrush and clothing.
Barclay said no one would have thought to look for polonium as a possible poison until the Litvinenko case, which occurred two years after Arafat's death.
"We are revealing a real crime, a political assassination," Suha Arafat told Reuters.
"This has confirmed all our doubts," said Suha Arafat. "It is scientifically proved that he didn't die a natural death and we have scientific proof that this man was killed."
She did not accuse any country or person, and acknowledged that the historic leader of the Palestine Liberation Organization had many enemies.
An investigation by the Qatar-based Al Jazeera television news channel first reported last year that traces of polonium-210 were found on personal effects of Arafat given to his widow by the French military hospital where he died.
Palestinian leader Yasser Arafat was poisoned to death in 2004 with radioactive polonium, his widow Suha said after receiving the results of Swiss forensic tests on her husband's corpse.
A team of experts, including from Lausanne University Hospital's Institute of Radiation Physics, opened Arafat's grave in the West Bank city of Ramallah last November, and took samples from his body to seek evidence of alleged poisoning.
The widow of Yasser Arafat has claimed that the former Palestinian leader was poisoned with radioactive polonium, al Jazeera has reported.
Peace talks between Israeli and Palestinian negotiators began in private today amid the expectation that they could quickly founder over the issue of Israeli settlements.
It was in stark contrast to the celebrations marking the homecomings of 26 Palestinian prisoners after years spent in Israeli jails.
ITV News' Middle East correspondent Geraint Vincent reports from Jerusalem:
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Palestinian families in the West Bank and Gaza welcomed home relatives who were earlier freed from Israeli jails.
Israel released 26 Palestinian prisoners, including some convicted of murder, on the eve of long-stalled Mideast peace talks.
Esmat Mansour said:"I feel great, I wished and waited for 20 years for this moment, to be here with my mother and father, and with my family and friends".
He received a 22 year sentence after being convicted of aiding a Palestinian cell that murdered an Israeli man in the settlement of Beit El.
Palestinian President Mahmoud Abbas welcomed some of the 26 prisoners released by Israel on Tuesday upon their much celebrated return to the West Bank.
The release was part of an agreement brokered by US Secretary of State John Kerry to get Israel and the Palestinians back to the table for peace talks that had stalled since 2008.
In toral, 104 convicts will be released in four batches, although their freedom is contingent on progress in peace talks.
Twenty-six Palestinian prisoners released by Israel have arrived in the West Bank and Gaza.
About a thousand people took to the streets of Ramallah in celebration, singing and dancing.
The move came ahead of Middle East peace talks due to take place later today.
Israel's release of 26 Palestinian prisoners, a bargaining tool towards the peace talks that continue in Jerusalem tomorrow, has begun tonight in the Middle East.
The prisoners are being driven towards their homes in the West Bank and Gaza, where they will be greeted as returning heroes.
ITV News Middle East Correspondent Geraint Vincent, though, found their freedom has stirred real emotion on both sides: