CAIRO — Human Rights Watch called Sunday on Egypt’s military-backed government to immediately release from detention five aides of ousted Islamist President Mohammed Morsi.

The New York-based advocacy group said in a statement that the five have been held at an undisclosed destination since July 3, the day when the military ousted Morsi after millions demonstrated demanding he step down.

It said the five were among nine close Morsi aides detained that day. The other four have been transferred to regular prisons and are facing criminal charges.

“What kind of roadmap is this where a military-backed government can brazenly disappear former presidential aides for 150 days without any explanation?” said Sarah Leah Whitson, Middle East and North Africa director at Human Rights Watch. She was referring to the roadmap for a post-coup return to democracy announced by military chief Gen. Abdel-Fattah el-Sissi when he toppled Morsi, Egypt’s first freely elected president.

“Forcibly disappearing people for months on end doesn’t inspire confidence that this government intends to follow the rule of law,” she added. “The prolonged enforced disappearance of anyone is a crime, pure and simple. The Egyptian authorities should immediately free them unconditionally.”

According to HRW, the five still held at a secret location are: Essam el-Haddad, Morsi’s top foreign policy adviser, Ayman Ali, who advised him on the affairs of Egyptian expatriates, aide Ayman el-Serafy, media adviser Abdel-Meguid el-Meshaly and foreign affairs aide Khaled el-Qazzaz.

There has been no word from the military or the government it backs on the fate or whereabouts of the five, but there have been reports in the local media linking some of them to ongoing criminal investigations, chiefly to do with conspiring with foreign powers against the country.

The HRW report comes at a time when authorities are pressing ahead with a harsh crackdown on Morsi’s Muslim Brotherhood. Already, thousands have been arrested, including most of the Brotherhood’s top leaders, and hundreds killed in the crackdown. Morsi himself was held at an undisclosed military facility until last month when he appeared in court along with 14 other Brotherhood leaders to face charges of inciting murder outside the presidential palace in December last year.

HRW said the five Morsi aides who remain in detention have been allowed limited communication with their families but that they had not yet spoken to lawyers.

In renewed protests, several hundred Cairo University students torched a police truck outside the institution’s main campus in the capital’s Giza district and briefly blocked traffic in the area, according to security officials and footage by The Associated Press Television from the scene. The officials spoke on condition of anonymity because they were not authorized to brief the media.

Some flashed the four-finger sign that the Brotherhood and its allies have adopted to commemorate the victims of the crackdown. Morsi’s supporters have been staging almost daily street protests since his July ouster to call for his reinstatement.

Recently, groups that opposed Morsi have also taken to the streets to denounce the military-backed government’s passage of a law that puts new restrictions on protests. It is seen by rights groups at home and abroad as a major setback to the country’s transition to democratic rule.

Copyright 2013 The Associated Press.