The Palestinian leader, Yasser Arafat, flew by helicopter out of his Ramallah compound early Friday to receive emergency medical treatment in Paris for an undetermined ailment that has left him weakened and unable to eat.

Several hundred Palestinian officials and security officers cheered and waved at Arafat, pressing against his car as he was driven the dozen yards from his offices and a makeshift medical clinic to a waiting Jordanian military helicopter inside his walled compound. The helicopter and an escort chopper lifted off in a swirl of rocks and debris under a leaden sky at 7:20 a.m. as his associates and employees waved an emotional farewell. He will be flown to Amman, the Jordanian capital, then will be taken by airplane to Paris, Palestinian officials said.

Israel's prime minister, Ariel Sharon, has guaranteed that Arafat, 75, will be allowed to return to Ramallah after medical procedures are completed, said Nabil Shaath, the Palestinian foreign minister. Arafat had not left his battered headquarters compound in the West Bank in more than two years.

"All his doctors agreed that he needs a hospital, someplace where all kinds of tests can be made safely and he can be a bit isolated from the millions of people who try to kiss him," Shaath said in a telephone interview Thursday from Amman, the capital of Jordan.

U.S. officials were consulted about Arafat's medical evacuation to Paris, Shaath said.

In Tel Aviv, a spokesman for the U.S. Embassy said, "We understand that Israel will let him back, and we agree with that."

Shaath said that Arafat, whose condition has deteriorated dramatically in the past two weeks, had been examined by teams of doctors from Tunisia, Egypt and Jordan. But Shaath said the cause of his illness remained unknown.

Palestinian officials and Arafat associates say he has been unable to eat and suffers from vomiting and diarrhea. They have offered conflicting explanations for the symptoms, ascribing them at different times to a severe flu, an intestinal infection, gallstones and a blood disorder, possibly leukemia.

"Tests show he is suffering from weakness in blood platelets, but his health condition is good," one of Arafat's personal physicians, Ashraf Kurdi, told reporters at the Ramallah compound. He said Arafat did not have leukemia.

"His red blood cell count has gone down, but this happens when you've been two weeks without food," Shaath said. "He has a general weakness as a result of 16 days now with very, very, very little feeding, and he has been fasting on top of that" because of Muslim restrictions on eating and drinking between sunrise and sunset during the holy month of Ramadan.

"He is very weak, frail and pale," Shaath said.

Arafat's office released a video Thursday showing the Palestinian leader slumped in a chair wearing gray pajamas and a stocking cap. He was gaunt but smiling, and was surrounded by several doctors and bodyguards.

Arafat's wife, Suha, who lives in Paris, arrived at his compound Thursday night after receiving a special permit from Israel. It was reportedly her first visit with her husband in more than four years.

Raanan Gissin, a spokesman for Sharon, said that Israel had agreed to allow Arafat to travel abroad for treatment because advanced medical facilities, such as MRI machines, are not available in the West Bank. He added that Arafat had refused to be treated in Israel.

"We allowed him to go to any hospital his doctors recommended so he can undergo very penetrating tests that they can only do with advanced equipment that they don't have in Ramallah," Gissin said. "We respected that. It's a legitimate reason."

On Thursday night, bulldozers cleared away battered, rusted cars and other debris from parking lots surrounding Arafat's headquarters, making way for the helicopter to land Friday morning. The debris was distributed around the headquarters to obstruct the advance of Israeli troops and armored vehicles.

In the past, Arafat has been reluctant to leave his compound, expressing fears that he would be snatched by Israeli soldiers and forced into exile. Sharon, who on numerous occasions has said that Israel was considering evicting Arafat, also has made veiled threats against his life. Sharon refuses to negotiate with Arafat, accusing him of sponsoring terrorism and sending Palestinian suicide bombers into Israel.

Shaath said that, in Arafat's absence, Palestinian affairs would likely be administered by Ahmed Qureia, the Palestinian prime minister, and another senior official, Mahmoud Abbas, also known as Abu Mazen, who preceded Qureia as prime minister but resigned in a power struggle with Arafat about a year ago. Their responsibilities would require confirmation by the central committee of Fatah, the political movement that Arafat heads, Shaath said.

If approved by Fatah, he said, Qureia would temporarily take over Arafat's duties as leader of the Palestinian Authority, the body that governs the West Bank and Gaza Strip, and Abbas would assume Arafat's responsibilities as chairman of the Palestine Liberation Organization.

The deterioration in Arafat's medical condition has renewed debate among Palestinian officials and political analysts over Arafat's authoritarian rule and unmatched stature, which have inhibited the rise of potential successors. Many politicians and analysts said they feared Arafat's death would fuel chaotic and divisive power struggles among rivals vying to take his place.

"The situation with Yasser Arafat is very critical," said Hani Masri, a political analyst based in Ramallah. "He has many of the cards in his hand, he has most of the Palestinian power, he is the spiritual leader, and Palestinian institutions are very weak. When he goes, there will be a lot of fighting."

But some Palestinian leaders said they were not dismayed by the prospect of change in Palestinian governing institutions.

"Many people on a human level are saddened that the absence of the president will close a chapter in the life and history of the Palestinian people," said Ziad Abu Amr, an independent Palestinian legislator from Gaza City who has criticized Arafat's failure to accept reforms. He said that under Arafat, "the Palestinian system became paralyzed, with no exercise of leadership."

A photo released by the Palestinian Authority shows a smiling Yasser Arafat with doctors at his compound.Nabil Abu Rdeneh, seated at right, an adviser to Yasser Arafat, and Ashraf Kurdi, one of the Palestinian leader's physicians, address reporters at the compound in Ramallah.Workers clear space for a helipad, left, ahead of Arafat's planned departure for Paris, home of his wife, Suha, above. Arafat's ailment remains unidentified.