The Interior Ministry said that Ayman Hadhoud had been placed in a psychiatric unit for attempting to break into an apartment in the capital Cairo, and carrying out what it called "irresponsible acts".

The family was told on Sunday to collect his body as he had died recently, but they have refused to do so without an established cause of death.

The public prosecutor has now ordered an autopsy.

Human rights groups in Egypt are calling on the government to address the issues of forced disappearances and deaths in custody.

Mr Hadhoud, who worked as a financial auditor at the American University in Cairo, ran in election in 2010 against the director of then President Hosni Mubarak's office.