Karimov was hospitalized early on Saturday after suffering a stroke.
"With a heavy heart that we inform you that in the past 24 hours the condition of our president saw a sharp deterioration and is considered critical by the doctors," a Friday statement released by Uzbekistan’s Cabinet says.
The statement confirms that Karimov had suffered a stroke.
"As it was reported earlier, the head of our state, Islam Abdugʻaniyevich Karimov was hospitalized last Saturday after having suffered a stroke," the statement says.
The reports of Karimov's death were previously dismissed by a source in the Uzbek Presidential Office.