Egypt's former head of intelligence Omar Suleiman, one of ousted President Hosni Mubarak's most senior officials, died in the United States where he was undergoing medical tests, Suleiman's assistant told Reuters on Thursday.

"He was fine. It came suddenly while he was having medical tests in Cleveland hospital," said the aide, Hussein Kamal, without giving a reason for Suleiman's death.

The former intelligence chief stepped briefly into the limelight when he was made vice president days before Mubarak was ousted in a popular uprising last year.

A veteran confidant of Mubarak, Suleiman had headed the Egyptian General Intelligence Services (EGIS) since 1993, taking on a prominent diplomatic role in Egypt's relations with Israel, Palestinian factions and aid donor and ally the United States.

He was quietly touted as a possible successor to Mubarak although many Egyptians believed the autocratic president would serve for life or try to hand power to his son.

After more than a year away from the public gaze, Suleiman returned to the fray this year, making a brief bid for Egypt's presidency until he was disqualified for failing to win enough signatures to take part.

He later left the country, travelling to Abu Dhabi with relatives, according to a person familiar with the matter.

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