Quoting "very good sources", France's Le Monde newspaper said on Wednesday that it was internal lesions associated with disseminated intravascular coagulation (DIC) which led to the sudden deterioration of Arafat's condition four days after his arrival at a Paris military hospital on 29 October.
On 3 November the Palestinian leader fell into a coma from which he never recovered.
Le Monde quoted doctors as saying that DIC is a condition rather than a disease, and can be set off in a person of Arafat's age - 75 - by either an infection or a cancer. However, they had found no indication of either.
"We also worked on the question of poisoning, using sophisticated techniques, before concluding with a negative," it quoted a doctor as saying.
Le Monde said: "DIC is the complete disruption of the mechanisms which normally assure proper blood clotting... It can lead to major internal bleeding and possible death."
French medical secrecy laws mean that the report on Arafat's death has been communicated only to his immediate family, resulting in a spate of rumours in the Arab world that he may have been poisoned.
An online medical dictionary describes DIC as a condition under which "blood-clotting mechanisms are activated throughout the body instead of being localised to an area of injury.
"We also worked on
the question of poisoning, using sophisticated techniques, before concluding with
Doctor quoted in Le Monde
"Small blood clots form throughout the body, and eventually the blood-clotting factors are used up and not available to form clots at sites of real tissue injury."
Meanwhile, the Spanish daily El Pais published an interview with Arafat's personal doctor, Ashraf al-Kurdi, who said that though he did not believe his patient was poisoned, he had considered the possibility.
"All the other pathologies that could have set off Yasir Arafat's symptoms were discounted one after the other," al-Kurdi, a former Jordanian health minister, said.
"If it was a poison, then it must have been strong to kill so quickly. I still don't believe it was that."
The French government spokesman Jean-Francois Cope said that if there had been any suspicion of poisoning, doctors treating Arafat would not have released his body.
Arab states are rife with rumours
over the cause of Arafat's death
"Mr Arafat received the best possible care and all the tests that had to be taken were taken. If the doctors had had any doubt, they would have had recourse to the justice system.
"But I note that the authorisation to dispose of the body was duly issued," he said.