PARIS - Yasser Arafat has lapsed into a coma in a French hospital, a senior Palestinian official said today, a day after the Palestinian leader was rushed to intensive care following a sharp deterioration in his health.

The official would not say when Arafat lost consciousness. Two Arafat aides denied he was in a coma, but the senior Palestinian with close access to the medical team insisted Arafat was comatose.

French hospital officials would not comment. The 75-year-old leader was rushed to the Percy Military Training Hospital outside Paris for emergency treatment Friday. Since then, his condition has largely remained a mystery, with Palestinians issuing conflicting reports.

Israeli media, citing Israeli intelligence officials, said Arafat suffered organ failure and lost consciousness several times. The Maariv daily said his condition was "very critical."

Anxious Palestinian leaders held an emergency meeting in the West Bank today. 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.

There is concern in Israel about the potential for chaos in the West Bank and Gaza Strip if Arafat dies or is incapacitated to the point where he is unable to perform politically. The Israeli army has a plan, called "new leaf," 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.

Israeli security officials were meeting today to study the repercussions in the Middle East should Arafat die, Israeli officials said. Top officials, including Israeli Defense Minister Shaul Mofaz and Army Chief Lt. Gen. Moshe Yaalon, were to focus their weekly meeting on reports that Arafat's health took a sudden turn for the worse, the officials said.

Among Israel's plans are ways to prevent Arafat from being buried in Jerusalem. 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.

Cabinet official Saeb Erekat called reports Arafat had lapsed into a coma "baseless." Erekat told The Associated Press in Ramallah that Arafat's wife, Suha, told him Arafat's condition was "stable but difficult."

Shaath said, "He is not getting better but not getting worse either. He is being examined. He is not in a coma. There is no explanation for what has happened."

Mohammed Rashid, Arafat's financial adviser, also denied that Arafat was in a coma.

"Last night, several blood and bone marrow tests were done that required the president to be in an isolation unit for several hours, and there is no truth to any of the reports that he is in a coma," Rashid said in Paris.

Earlier today, Palestinian officials said Arafat had lost consciousness repeatedly and described his condition as extremely serious.

Arafat's condition worsened Wednesday and he was rushed into intensive care. Doctors do not know the cause of the blood and digestive disorders uncovered over the past few days.

Arafat, who fell ill three weeks ago, was flown to France after passing out briefly at his West Bank headquarters. He was initially described as having a bad flu, with symptoms of vomiting and diarrhea.

Palestinian officials insist publicly that leukemia and other forms of cancer, as well as any type of poisoning, have been ruled out.

The officials, undoubtedly conscious of the anxiety at home at the thought of a future without Arafat - who has led the Palestinians for 40 years with no obvious successor, previously described his condition as improving.

Rashid said early today the medical analysis was "deepening a little bit" but he remained confident Arafat would recover.

"There are no setbacks," he said. "It's no secret he's ill, that's why he's in France. But there is no threat, there is no danger, no serious degradation."