According to Egypt’s MENA news agency, Mubarak was declared clinically dead upon arrival at a military hospital in southern Cairo late on Tuesday.
The demonstrators have been at Tahrir Square since Tuesday to protest against the dissolution of parliament by the Supreme Council of the Armed Forces (SCAF).
The demonstration was called by the Muslim Brotherhood, which says the dissolution of the parliament was a constitutional coup against last year’s revolution.
Egypt’s ruling military council formally announced the dissolution of the parliament on June 16 following an earlier Supreme Court ruling.
Under a constitutional declaration issued late on Sunday night, the junta also took control of the state budget and gave itself veto power on a new constitution, making the new president almost powerless.
Egyptians cast their ballots in a two-day presidential runoff election on June 16 and 17, which pitted the candidate of the Muslim Brotherhood’s Freedom and Justice Party, Mohammed Morsi, against former Prime Minister Ahmad Shafiq.
Both Morsi and Shafiq are claiming victory in the runoff. Official results are expected to be announced on Thursday. .