Doctors fought to keep Yasser Arafat (search) alive as anxious Palestinian officials looked for ways to prevent unrest if their 75-year-old leader, said to be in a coma Friday, dies.

A swirl of reports saying Arafat had died Thursday were quashed by doctors at the French military hospital where he has been treated since being airlifted to France last week. Arafat's aides, however, acknowledged his condition was very serious.

On Friday, Israeli Justice Minister Yosef Lapid (search) told Israel TV's Channel Two that Arafat was brain dead and on life support. But a Palestinian spokeswoman denied Lapid's assertion.

"He is in a coma. We don't know the type but it's a reversible coma," Leila Shahid, the Palestinian envoy to France, told French RTL radio.

Shahid said Arafat was put under anesthesia to have medical tests, including an endoscopy and a biopsy of the spinal cord.

"The doctors don't have a diagnosis," she said. "All vital organs are functioning. This is why all the doctors say that he could or could not wake up."

Arafat's chief of staff, Ramzi Khoury (search), called an Associated Press reporter on Thursday and said: "I am standing next to the president's bed, he is in grave condition."

Prime Minister Ahmed Qureia received greater authority to deal with urgent financial matters, said committee member Qais Abdel Karim. Palestinian leaders huddled all day Thursday in urgent meetings.

Qureia will meet with security chiefs in the Gaza Strip on Friday to ensure that no internal conflict erupts in the volatile territory at a time of uncertainty, a Palestinian official said on condition of anonymity.

Outside the hospital, some 50 well-wishers held a vigil into the early morning hours Friday. Some held candles, others Arafat portraits; a large Palestinian flag hung from the hospital's outer wall.

"It tears your heart up," said Mahmod Nimr, 36, an unemployed Palestinian by the main gate of the hospital. "I can't see someone taking his place."

On a day of high drama, there were persistent and contradictory reports about Arafat's condition. Luxembourg's prime minister announced at a summit of European leaders in Brussels Thursday that Arafat had died, but his spokesman later said it had been a "misunderstanding."

Contradicting reports that Arafat was brain dead, the Palestinian leader's personal physician, Dr. Ashraf Kurdi, said a brain scan showed Arafat had not suffered a hemorrhage or stroke, and "has no type of brain death."

Brain death occurs when the brain stops working, making it impossible for the body to maintain its own vital functions. It is irreversible. Patients can be kept alive by a machine, as long as the heart is still beating and nothing is seriously wrong with the rest of the body.

French television station LCI quoted an anonymous French medical official as saying Arafat was in an "irreversible coma" and "intubated" — a process that involves threading a tube down the windpipe to the lungs to connect it to a life-support machine to help the patient breathe.

To be on life support, a patient must be unconscious, but not necessarily brain dead or even in a coma.

A Palestinian official in Gaza who is close to Arafat's wife, Suha, said she told him Arafat fell unconscious after receiving a strong anesthetic for a biopsy.

The official, who spoke on condition of anonymity, quoted her as saying Arafat was recovering.

Palestinian leaders held an emergency meeting in the West Bank, and Foreign Minister Nabil Shaath said top officials were in touch with Arafat's hospital every 30 minutes to check on his condition.

"The Palestinian leadership is in constant meeting to follow up on the president's health," Shaath said from Ramallah, where leaders of the PLO and Arafat's Fatah movement were meeting.

A prolonged Arafat incapacitation — or death — could have profound impact on the Middle East. There are fears of unrest among Palestinian factions, which Arafat, viewed as a national symbol by even some who opposed him, was largely able to prevent. Chaos in the West Bank and Gaza could make any cooperation with Israel even more difficult.

On the other hand, Israel and the United States have in recent years shunned Arafat as a terrorist and an obstacle to peace, and his replacement by a new leadership could open the door to renewed peace talks. Such a scenario could affect Israel's current plans to pull soldiers and settlers out of the Gaza Strip in a unilateral move not coordinated with the Palestinians.

The Israeli army, which is on high alert, has a plan to deal with the fallout from Arafat's death, including possible Palestinian riots. The Israeli military had not yet moved forces to anticipated problem areas, but commanders were told to be on standby.

Among Israel's plans are ways to prevent Arafat from being buried in Jerusalem. Israeli Prime Minister Ariel Sharon has said he would not permit Arafat to be buried in the city, claimed by both Israel and the Palestinians as their capital.

Army chiefs said they were opposed to Arafat's burial in Jerusalem or the nearby suburb of Abu Dis in the West Bank. Arafat's family has a plot in the Gaza Strip.

Arafat was taken to intensive care after his condition worsened Wednesday. French President Jacques Chirac went to the hospital Thursday and saw Arafat and his wife, "to whom he expressed his best wishes," Chirac's office said. The president also met members of the Palestinian Authority and doctors.

French physicians have not revealed Arafat's illness and his condition has largely remained a mystery.