"The doctors exclude for the time being any possibility of leukaemia. There are other possibilities," the Palestinian envoy to Paris, Laila Shahid, said on Saturday.
Arafat was carried into a French military hospital in the Paris suburb of Clamart on Friday, after arriving by helicopter at the end of a six-hour journey from his shell-battered compound in the West Bank city of Ram Allah.
Earlier, one of Arafat's senior aides, Jibril al-Rajub, played down talk of cancer in an interview to Aljazeera.
"Initial checks confirm that his case is fine. The possibility that the president has cancer has been ruled out," al-Rajub said. "All initial checks indicate that the president will regain his health very soon."
Doctors said it will take several
days before a accurate diagnosis
Shahid told reporters on Friday Arafat has had intestinal flu for at least three weeks, "but obviously there is more to it than that". Doctors needed "several days" to form an accurate diagnosis.
US Secretary of State Colin Powell said he was "pleased that (Arafat) is now in a sophisticated medical facility where his health condition can be more carefully assessed. And I trust he will get the treatment that he needs".
Powell made his comments in an interview with Egyptian television on Friday, a transcript of which was released by the US Department of State.
The future of Arafat as the Palestinian leader is now unclear, and there are fears that his departure will create a power vacuum.
An Israeli security source said of Prime Minister Ariel Sharon's decision to allow his long-time foe to return after treatment: "We assessed Arafat's condition is irreversible and that it will eventually lead one way or the other to his disappearance from the political arena.
"That assessment led Sharon to decide to allow him to come back if doctors recommended, in the calculation that this scenario would probably never arise."
Arafat's declining health has raised fears of chaos among Palestinians.
The death of a leader regarded by Israel and its US ally as an obstacle to peace could also shuffle the cards in the Middle East conflict as the US heads into a presidential election on Tuesday.
Washington says Palestinians would be better off governed by a prime minister with control of all the security forces.
"That individual, so empowered, would give the Israelis a partner for negotiations," Powell said. Arafat might then take on another role within the Palestinian community.
Arafat has named no successor nor appointed an acting resident to cover for him during his treatment.
Officials in the West Bank said Prime Minister Ahmad Quraya
Abbas will run the Palestinian
would run the day-to-day affairs of the Palestinian Authority. Former prime minister Mahmud Abbas will run the Palestine Liberation Organisation.
Abbas is due to head a PLO meeting in Arafat's compound on Saturday, Palestinian officials said. "It's going to be a routine meeting to ensure the functioning of the Palestinian institutions," PLO member Yasir Abd Rabbu said.
Should Arafat die, parliamentary speaker Rawhi Fattuh would replace him as Palestinian Authority president for a 60-day period during which elections would be held.