The health of the jailed former president, who was overthrown in a popular uprising last year, has deteriorated rapidly in recent weeks.
The official, speaking on condition of anonymity because he is not authorized to talk to the media, added that Mubarak lives only on liquids and yogurt.
Mubarak was sentenced to life in jail earlier this month for his role in the killing of hundreds of protesters in the protests that led to his downfall.
Mubarak’s critical condition comes just a week ahead of Egypt’s first genuinely democratic presidential election in which the fate of the former strongman remains a crucial issue.
Former Mubarak-era prime minister Ahmed Shafik will face off against Muslim Brotherhood candidate Mohammed Mursi, with both men accusing the other of being opposed to the revolution that brought about Mubarak’s downfall.