The spokesman Alaa Mahmoud says the 84-year-old Mubarak was moved by ambulance from the hospital in Torah Prison to nearby Maadi Hospital in southern Cairo. The military facility is where Mubarak's predecessor Anwar Sadat was declared dead after being shot by Islamic extremists in 1981.
Earlier, the state news agency said Mubarak's health condition rapidly deteriorated, with his heart stopping briefly, then suffering a stroke.
Mubarak was sentenced to life in prison on June 2 for failing to stop the killing of protesters in last year's uprising that led to his ouster.