Paris ? Yasser Arafat, battling an unexplained illness, underwent a new round of tests early today after his condition took a sudden turn for the worse, Palestinian officials said.

The officials, speaking on condition of anonymity, said the Palestinian leader remained in intensive care at a French military hospital where he had been undergoing treatment for a week.

He was rushed into intensive care Wednesday after his condition seriously deteriorated, the sources said, adding that he was undergoing tests.

They did not elaborate on the type of tests. Doctors have determined Arafat is suffering from blood and digestive disorders, but they still don’t know the cause, the sources said.

French hospital and military officials refused to comment, but more information was expected from a news conference scheduled for this afternoon.

Meanwhile, Arafat’s top aides denied there had been any setback and accused Israel of spreading rumors. The report first aired on Israel’s Channel Two television, which cited unidentified Palestinian officials.

“These unfounded reports are not coming from French medical teams, these are leaks from the Israeli side,” said Mohammed Dahlan, a former Palestinian security chief.

Arafat has led the Palestinians for 40 years with no obvious successor.

Khaled Salem, Arafat’s top aide, said early Thursday that the medical analysis was “deepening a little bit” but he remained confident Arafat would recover.

“There are no setbacks,” he told reporters outside the hospital. “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.”