Ailing Palestinian leader Yasser Arafat is undergoing urgent medical treatment in France for a mystery illness.
Crowds of supporters waved off Yasser Arafat from Ramallah
Mr Arafat, 75, travelled from his Ramallah compound to an air base near Paris, from where he was flown by helicopter to a military hospital.
A Palestinian spokeswoman said he had gastric flu, but there was more to his illness and diagnosis would take days.
The Palestinian Authority, the prime minister and legislative council will take over leadership in his absence.
Mr Arafat had been suffering stomach pains for more than two weeks before his condition worsened sharply on Wednesday night, prompting doctors to recommend treatment abroad.
Blood tests have revealed that he has a low count of platelets - responsible for clotting - but his doctors have rejected Israeli suggestions that he could be suffering from stomach cancer.
Security has been tightened at the hospital treating him, which has more than 100 doctors and specialises in blood disorders.
It is the first time in nearly three years that Mr Arafat has left the half-ruined compound in the West Bank, to which he has been confined by Israeli forces.
Mr Arafat set out from Ramallah on Friday morning, travelling by helicopter to the Jordanian capital, Amman.
Wearing a military overcoat, Mr Arafat waved to officials and bodyguards as he left his compound, while a large crowd of chanting supporters surrounded the helicopter.
Video footage of Arafat with his aides was shown on Thursday
Mr Arafat was accompanied by his wife, Suha, who had arrived in Ramallah from Paris a day earlier to see her husband for the first time in four years.
A French military jet flew the Palestinian leader from Amman to the Villacoublay air base, from where he was transferred by helicopter to the Percy military hospital in Clamart, near Paris.
The French defence ministry said Mr Arafat's arrival had been delayed after his plane had to skirt around Israeli airspace because France has no permanent overflight agreement.
Sources close to French President Jacques Chirac told the AFP news agency that Mr Chirac had personally made the decision to accept a request from the Palestinian Authority to treat Mr Arafat.
Speaking in Rome, the French president said it was natural for France as "a land of refuge" to admit the Palestinian leader.
Palestinian Foreign Minister Nabil Shaath, who travelled with Mr Arafat to Amman, said his leader had become "very weak, quite frail", with significant weight loss over 16 days of illness.
He insisted Mr Arafat's absence would be temporary, saying: "He is a sick man who needs treatment. That is the first thing on our mind, and for that he should be given time in hospital."
In Ramallah, Mr Arafat's mother-in-law Reemonda Tawil said the Palestinian leader was in good spirits but people were fearful.
"We all hope that he will come back safe to us," she said. "It's very moving, everybody is crying.
"He is more than a spiritual leader - he is a father, he is everything to us."
Israel's government has said it will not hinder Mr Arafat's return to the West Bank after his treatment.
But Israeli defence and foreign ministers on Friday suggested they might oppose that position.
Arafat adviser Nabil Abu Rudeinah insisted Israel had agreed to guarantees sought by the US, European and Arab nations that Mr Arafat would be allowed back.
The BBC's Barbara Plett says Israel, which has long held Mr Arafat responsible for militant violence, is probably keen not to be seen as responsible in any way for the death of the Palestinian leader.
Washington has said it hopes Mr Arafat will get the "medical care that he needs to return to health".
There is a huge sense among Palestinians that this is a moment of crisis, the BBC's Alan Johnston reports from Gaza City.
He says there is little talk now of Mr Arafat's failings as an administrator and ordinary Palestinians are very much hoping that the old man, as they often call him, will pull through.