Hosni Mubarak's health has entered a "dangerous" phase and doctors have had to use a respirator five times to help the deposed Egyptian leader breathe, according to security officials at his prison.
Mubarak's health crisis came days after he was sentenced to life in prison for failing to stop the killing of protesters in the uprising that unseated him last year.
The officials at Torah prison, south of Cairo, said Mubarak, 84, was suffering from shock and high blood pressure as well as breathing problems. Specialists were called in to examine him, and a transfer to a military hospital is being considered, said the officials.
Mubarak was sentenced to life on Saturday, but he and his two sons - one-time heir apparent Gamal and wealthy businessman Alaa - were acquitted of corruption charges. The sons are also being held in Torah awaiting a separate trial on charges of insider training.
The officials said prison authorities were allowing Gamal to be by his father's side. Alaa also applied for permission, but it has not yet been granted, said the officials.
Though Mubarak's authoritarian regime was widely unpopular by the time of his overthrow last year, conditions in Egypt have deteriorated since then, with a wave of deadly protests, a battered economy and seemingly endless strikes.
Some evidence of displeasure over conditions could be seen in the second-place finish by Mubarak's last prime minister, Ahmed Shafiq, in the first round of presidential elections last month, ahead of more liberal candidates.
Shafiq is facing Muslim Brotherhood candidate Mohammed Morsi in a run-off election on June 16-17, but it could still be called off.
A spokesman for Egypt's highest court said it would look into whether a "political exclusion" law is constitutional on June 14, two days before the run-off. The law bans senior officials who served in Mubarak's regime starting in 2001 from running for office. It applies to prime ministers, vice presidents and senior members of Mubarak's now-dissolved ruling party.
If upheld, it could mean that Shafiq could not run - possibly forcing cancellation of the run-off and a repeat of the first round.