Naguib Mahfouz, the only Arab writer to win the Nobel Prize for Literature, has been moved to the intensive care ward of an Egyptian hospital.
A hospital spokesman said Mahfouz, who is 94, is suffering from kidney dysfunction and other ailments.
Mahfouz won the Nobel Prize in 1988 mainly for his Cairo Trilogy, published in the 1950s. He has been a champion of moderation and has opposed Islamic extremism.
The Cairo Trilogy, comprising three books, portrays several generations of an Egyptian family. The books are set in old neighborhoods of the city where Mahfouz grew up.
In awarding the prize, the Nobel committee cited Mahfouz for works it said were rich in nuance. It said he formed an Arabian narrative that applies to all mankind.
Mahfouz's style has been compared to the French writer Honore de Balzac.
Some information for this report was provided by AFP, AP.