Suha Arafat spoke to The Associated Press by phone from the Qatari capital of Doha after receiving the results of the Swiss team's examination of her husband's remains.
The 108-page report on the findings was published yesterday by the Qatar-based satellite TV station Al-Jazeera. The station, along with Mrs Arafat, had initiated the renewed investigation of Arafat's death last year.
Earlier this year, Arafat's grave was exhumed. The Swiss report said Arafat's remains and burial soil contained elevated levels of polonium-210, a rare and lethal substance.
Mrs Arafat confirmed the authenticity of the Swiss team's report published by Al-Jazeera.
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The Palestinian leader died in November 2004 at a French military hospital, a month after falling violently ill at his Israeli-besieged West Bank compound. Palestinian officials have alleged from the start that Israel poisoned Arafat, a claim Israel denies.
In her comments today, Suha Arafat did not mention Israel, but argued that only countries with nuclear capabilities have access to polonium.
"I can't accuse any one, but it's clear this is a crime, and only countries with nuclear reactors can have and do that," she said.
Israeli officials vehemently denied any role in Arafat's death.
Paul Hirschson, a Foreign Ministry spokesman, dismissed the allegations as "hogwash."
Former Israeli official Dov Weisglass said Israel had no motive to kill Arafat at a time when he had been sidelined and isolated at his West Bank compound.
"I can assure you that officially, Israel had nothing to do with it," Weisglass, a senior adviser to then-Israeli Prime Minister Ariel Sharon, said in a phone interview.
Polonium can be a byproduct of the chemical processing of uranium, but usually is made artificially in a nuclear reactor or a particle accelerator. Israel has a nuclear research centre and is widely believed to have a nuclear arsenal, but remains ambiguous about the subject.
Mrs Arafat said the Swiss experts told her that had the remains been examined a year later, traces of polonium would have vanished.
The Palestinian Authority and Arafat's successor, Mahmoud Abbas, have so far withheld comment. Abbas was in Amman, Jordan, for a meeting with US Secretary of State John Kerry, on the fate of slow-moving Israeli-Palestinian peace talks.