Israel, seen by many Arabs as the prime suspect behind the mysterious illness that killed the 75-year-old Arafat in 2004, sought to distance itself anew from the death of the man who led Palestinians' bid for a state through years of war and peace.

A Swiss institute which examined clothing provided by Arafat's widow for a documentary by Qatar-based al-Jazeera television said its radiation detection experts had found "surprisingly" high levels of polonium-210, the same substance found to have killed a former Russian spy in London in 2006.

But it said symptoms described in the president's medical reports were not consistent with the radioactive agent.

"I want the world to know the truth about the assassination of Yasser Arafat," widow Suha Arafat, 48, told al-Jazeera, without making any direct accusations.

Allegations of foul play - and of Palestinian involvement in it - have long marked factional fighting among Palestinians. The latest revelation coincides with renewed tensions within Arafat's Fatah movement, now headed by his successor, President Mahmoud Abbas, and between Fatah and Hamas, the Islamist movement which controls the Gaza Strip.

Abbas's administration said it would approve Arafat widow's request to bring her late husband's remains out for autopsy from a limestone mausoleum built next to his headquarters in the West Bank city of Ramallah, without giving a date for such a move.