A senior palestinian official has told the reuters agency that it is susepcted that Yasser Arafat has leukemia.
A spokesman for the Palestinian leader said he will not name an acting president to replace him while he seeks medical treatment abroad.
Mr Arafat is due to fly to Paris for treatment tomorrow. Doctors earlier diagnosed him as suffering from a potentially fatal blood disorder.
They said the 75-year-old needed further tests carried out outside the West Bank where he has been kept under virtual house arrest for the last three years.
Palestinians have doubted Israeli assurances that Mr Arafat would be allowed to return to the West Bank if he left.
But Raanan Gissin, spokesman for Israeli Prime Minister Ariel Sharon, insisted Israel would help.
Earlier one of the doctors treating Mr Arafat said that he was suffering from a blood disorder and more tests were needed to determine the cause.
Meanwhile, crowds of Palestinians are reported to have gathered outside the compound.
Palestinian officials earlier denied reports that the 75-year-old president has been slipping in and out of consciousness.
Security forces are on high alert across the Palestinian territories.
Mr Arafat received a letter of good wishes from President Mary McAleese this morning. It was delivered to his headquarters by staff from the Irish representative office in Ramallah.
