A former aide to ousted Egyptian President Mohamed Morsi has been released from jail after 18 months in detention without charge, relatives say.

Khaled al-Qazzaz, who served as foreign affairs secretary under Morsi, was freed on Sunday on health grounds.

Relatives said Qazzaz, who had spent more than 400 days in solitary confinement, was held under guard at a hospital for the last two months.

“The guards at the door to his room came to him a couple of hours ago, and told him 'we've been ordered to leave and you're free to go,” Ahmed Attia, his brother-in-law told Reuters by telephone from Canada.

Attia said that Qazzaz is staying at his parents’ home in the Egyptian capital, Cairo and hopes to rejoin his wife and four daughters in Toronto, Canada, soon.

Egyptian officials were not immediately available for comment on Qazzaz’s release, but a public prosecutor said that Qazzaz was being released for health reasons.

The prosecutor said Qazzaz had been under investigation for inciting violence and joining a ‘terrorist group’, a reference to the Muslim Brotherhood.

Qazzaz's Canadian wife, Sarah Attia, said by telephone that “My husband had been detained for 558 days now, and he's never been charged.”

Qazzaz was arrested in July 2013 along with Morsi and eight other senior aides when the army removed Morsi’s Muslim Brotherhood from power.

Morsi was ousted in July 2013 in a military coup led by Abdel Fattah el-Sisi, the country’s current president and then army commander. Since then the government has launched a brutal crackdown on Morsi’s supporters.

The Muslim Brotherhood has been also blacklisted as a terror organization by the new Egyptian government.

Rights groups say the army’s crackdown on supporters of Morsi has left at least 1,400 people dead and 22,000 arrested, while some 200 people have been sentenced to death in mass trials.