Jerusalem (CNN) -- Officials at the hospital in Israel where former Prime Minister Ariel Sharon is being treated described him Thursday as being in "extremely critical" and "grave" condition, with his family is by his side. "In the last few hours there has been a deterioration in Ariel Sharon's medical condition," said a spokesman for Sheba Medical Center in Tel Hashomer. "He continues to be in critical condition." Earlier this week, the center's director, Zeev Rotstein, had said doctors were unable to stabilize Sharon's kidney function and other vital systems and that the danger to Sharon's life had grown. The 85-year-old has been in a coma for eight years and is suffering from multiple organ failure. News broke last week that his health had recently worsened.