Yasser Arafat, the ailing Palestinian leader who was flown to a French military hospital last week, was rushed to intensive care after suffering a setback and was undergoing a new round of tests, Palestinian officials said early Thursday.

The two officials, speaking on condition of anonymity, said that Arafat's condition had seriously deteriorated over the past day and that doctors who have been examining him still did not know the cause of his illness.

Top aides to Arafat, however, denied that there had been any setback and accused Israel of spreading rumors. The report first aired on Israel's Channel 2 television.

Khaled Salem, a top aide to Arafat, said early Thursday that the medical analysis was "deepening a little bit," but he remained confident Arafat would recover. "There are no setbacks."

Arafat, 75, left his shell-battered compound in the West Bank city of Ramallah for the first time in more than two years after receiving assurances from his longtime enemy, Israeli Prime Minster Ariel Sharon, that he would be allowed to return after undergoing treatment.

Arafat has suffered for months from an apparent stomach disorder and other ailments. But until Friday he had refused to seek medical treatment outside his compound, where he has been under virtual Israeli house arrest since March 2002, fearing that Israeli authorities would not allow him to return to Palestinian territory.

An aide said that Arafat felt well enough Wednesday to ask about the U.S. presidential election. A statement was later issued in Arafat's name congratulating President Bush on his reelection.