The two sons of ousted Egyptian President Hosni Mubarak were released from prison Monday, nearly four years after they were first arrested along with their father, authorities said.

Security officials said the pair, wealthy businessman Alaa and Mubarak's one-time heir apparent Gamal, walked free from Torah Prison in a southern Cairo suburb shortly after daybreak and headed to their respective homes in the capital's upscale Heliopolis suburb.

Interior Minister Mohammed Ibrahim, who is in charge of police and prisons, confirmed the release of the two, but would not say when they walked free. There has been intense speculation among activists in Cairo that they may actually have been secretly freed over the weekend.

The two, along with their father, still face a retrial on corruption charges, for which a date has yet to be set. Separately, the two sons also face trial on insider trading charges. Hearings resume in March. They had been acquitted of other charges.

Mubarak, 86 and ailing, stepped down in February 2011 in the face of a popular uprising. He and his two sons were arrested in April that year. Mubarak remains at a military hospital in a southern Cairo suburb although there are no longer any legal grounds for his detention