Suleiman was closely associated in the minds of many Egyptians with Mubarak’s repressive rule, and human rights groups accused him of involvement in the widespread torture of detainees.
Rights activist Gamal Eid said he had hoped to see Suleiman face trial for crimes committed during Mubarak’s rule, as well as give valuable evidence on what happened during last year’s revolt.
“One of the enemies of democracy in Egypt is not here anymore,” Eid said. “In the court cases, though, we lost a lot. He was the black box.”
Often seen as the eminence grise of Mubarak’s government, he only emerged fully into the limelight in late January 2011, when he was appointed vice president in what proved to be the regime’s final days.
His last-ditch attempt at concessions failed to quell the mass street protests that had paralyzed Egypt. He was soon forced to appear on state television, grim-faced, to announce Mubarak’s resignation.
A gangly man with a wry smile and a thin mustache, Suleiman briefly returned to public life this year when he announced he was running for the presidency, but he was disqualified after failing to gain enough signatures.
The Cleveland Clinic in Ohio, where Suleiman had been treated since Monday, said in a statement that he died of “complications from amyloidosis, a disease affecting the heart, kidneys and other organs,” the Associated Press reported.
The state-owned newspaper al-Ahram quoted an unnamed individual as saying Suleiman’s funeral would take place in Cairo on Friday and would be attended by Egypt’s top general, Field Marshal Mohammed Hussein Tantawi. On Twitter, many Egyptians objected to a proposal that Suleiman be granted a military funeral.
Born in 1936 in the southern Egyptian town of Qena, Suleiman enrolled in one of the country's premier military academies as a young man and served in three wars, including conflicts with Israel in 1967 and 1973.
He later became head of military intelligence and was promoted by Mubarak in 1993 to chief of the powerful national security intelligence agency.
Suleiman’s staunch opposition to Islamist groups won him support in Washington and Jerusalem, and he took on a prominent diplomatic role in Egypt’s relations with Israel, Palestinian factions and the United States. In 2009, Foreign Policy magazine ranked him as the Middle East’s most powerful intelligence chief, ahead of then-Mossad chief Meir Dagan.
According to State Department documents made public by the anti-secrecy organization WikiLeaks, Suleiman was a key partner of the CIA and the point man in Egypt on extraordinary rendition — the process by which the United States turned over detainees to other countries, some of which used torture as part of their interrogations.
“Our intelligence collaboration with Omar [Suleiman] is now probably the most successful element of the relationship,” a 2006 diplomatic cable read.
Before the Egyptian revolt, Suleiman was quietly touted as a possible successor to Mubarak, although many Egyptians believed the president would serve for life or try to hand power to his son Gamal.
Egypt’s interim government paid tribute to Suleiman in a statement Thursday, calling him a “patriotic, honest figure.”
He is survived by his wife and three daughters.
Ingy Hassieb contributed to this report.