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.
In my opinion, it is absolutely certain that the cause of his illness was polonium poisoning. The levels present in him are sufficient to have caused death.
What we have got is the smoking gun - the thing that caused his illness and was given to him with malice.
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.
Forensic investigators have taken samples from the body of the late Palestinian leader Yasser Arafat today after speculation that he may not have died from a stroke, but could have been poisoned by Israel.
ITV News' Middle East Correspondent John Ray reports:
After the body of former Palestinian leader Yasser Arafat was exhumed, it was taken to a nearby mosque so that Palestinian doctors could take samples from his bones, local officials told the Associated Press.
The samples will then be handed over to French, Swiss and Russian experts who have flown in for the exhumation and will examine them in their home countries.
Earlier, samples were also taken from Mr Arafat's bedroom, office and personal belongings, the report added.