Mr. Mubarak had been in a prison medical ward since the beginning of the month, when he was given a life sentence in connection with the killing of demonstrators during the 18 days of protests that ended his rule.
The news of his failing health spread quickly through Tahrir Square, the birthplace of the uprising, where tens of thousands of people were protesting the military council governing Egypt. In recent days, the generals had moved to seize the kind of uncontested authority that the former president wielded during his nearly three decades in power.
The confusion over his health injected new volatility into the country’s growing political and constitutional crisis, even as the two candidates to replace Mr. Mubarak as president both declared themselves the winners of the weekend’s election.
Analysts marveled that Mr. Mubarak had lost consciousness at the climactic moment of the struggle over the future of the system he had defined for so long, and just two days after the vote to choose his successor.
“It is very Shakespearean,” said Diaa Rashwan, an analyst at Al Ahram Center, a state-financed research institute. “To himself, he is eternal. There can be nobody after him. He does not want to hear the name of his successor.”