Arafat has been considerably pale and weak during some appearances the past week.
Britain’s Guardian newspaper quoted aides close to the 74-year-old as saying he had a “slight heart attack” last week, but it was kept under wraps for fear of creating panic.
Chief Palestinian peace negotiator Saib Uraikat dismissed the report on Wednesday.
On 29 September Arafat’s personal physician, Dr Ashraf al-Kurdi, hurried from Jordan to the president’s besieged compound in the occupied West Bank city of Ram Allah to examine him.
At the time, Arafat had been unable to keep down his food for three days and Palestinian sources said he feared that he had been poisoned.
Al-Kurdi described Arafat as being in relatively good health. However, Arafat has not improved since that visit, said his aides on condition of anonymity.
Israel has confined Arafat to his compound for nearly two years and has threatened to prevent him from returning if he leaves the Palestinian Territories.
Israeli foreign ministry officials said the Jewish state “probably would” permit Arafat to leave the compound if he needed to be treated at a hospital.
Israel has renewed calls to “remove” Arafat, raising fears the leader could be assassinated or expelled.