PARIS, France (CNN) -- A spokesman for the French military hospital housing Palestinian leader Yasser Arafat has told reporters the ailing leader is not dead.

He added though on Thursday that the 75-year-old leader had been moved to another department within the hospital for treatment more appropriate for his condition.

The announcement came after some wire services reported Arafat had died or was brain dead.

The hospital spokesman said the Palestinian leader was moved into the other department Wednesday, He said Arafat's condition had become more complex.

Senior Palestinian officials in Paris Thursday told CNN that Arafat was in critical condition after drifting in and out of consciousness throughout the night.

Meanwhile, the Israeli military has been placed on high alert and Palestinian security forces are reviewing their plans to keep Palestinian territories calm in the event of Arafat's death.

Thursday afternoon, French President Jacques Chirac was allowed to briefly visit Arafat's room. He also spent about a half hour with Suha Arafat, the Palestinian leader's wife.

Arafat's senior adviser, Nabil Abu Rudeineh, dismissed reports that the leader was in a coma, calling them "rumors."

"He is in the intensive care unit, as I said, because he is in need of several very advanced tests in the coming hours and days," Abu Rudeineh said.

In Ramallah, Palestinian Prime Minister Ahmed Qorei told reporters Thursday that Arafat was in stable but serious condition and still required urgent medical attention.

"He's under treatment in very honest hands, our friends the French," he said.

Palestinian Cabinet Minister Yasser Abed Rabbo said the cabinet is "concerned now with the health of Chairman Arafat and we hope that he will overcome his illness."

A source close to Arafat told CNN the Palestinian leader is "OK and he's resting" and denied reports that he had lost consciousness.

Another senior Palestinian source said Arafat had been medicated before tests Thursday morning and had simply slept through the night. Security plan

Earlier Thursday, executive meetings were held of Fatah -- the political party headed by Arafat -- and there was an emergency session of the central committee of the PLO, where officials discussed plans should Arafat's return be delayed for several weeks or months.

Palestinian security officials reviewed security plans in the event of Arafat's death, and Israeli media reported Thursday that the Israeli military is on high alert.

Israeli defense officials reviewed their "Operation New Page" security plan during a regularly weekly briefing, a plan that has been in place for some time.

Palestinian officials have said that Arafat is suffering from a blood disorder, but they have repeatedly denied reports that he has leukemia.

After confining Arafat to his Ramallah headquarters for more than two and a half years, Israel's government allowed him to fly to Paris for medical treatment last week. Doctors have been conducting tests on him since his arrival Friday.

"The situation is stable, that's what I was told," Palestinian chief negotiator Saeb Erakat said, after saying he spoke with with Arafat's wife and Palestinian U.N. envoy Nasser al-Kidwa, who is with the Palestinian delegation in Paris.

CNN Correspondents Fionnuala Sweeney in Paris, John Vause in Ramallah and Guy Raz in Jerusalem contributed to this report.