The judge in the September 15 hearing ordered the detention of wealthy businessman Alaa and one-time heir-apparent Gamal before adjourning the hearings until October 20.

The surprise decision by Judge Ahmed Aboul-Fetouh followed his rejection of a technical report that apparently cleared the pair of any wrongdoing.

Thursday's ruling to release the Mubarak sons on a bail of 100,000 pounds ($A7690) each came just hours after an appeals court accepted a motion moved by their defence lawyers to remove the judge who ordered their detention.

In their motion, the lawyers argued that the ruling was "unreasonable" given that the two men regularly attended hearings and their place of residence was known to authorities.

The ongoing insider trading trial centres on the purchase by the two brothers and their alleged accomplices of a large number of shares in a local Egyptian bank that they allegedly knew was to become the target of a takeover by Arab Gulf investors.

The takeover was virtually certain to dramatically drive up share prices.

The brothers along with their father were first detained two months after a popular uprising forced the senior Mubarak to step down in February 2011 after 29 years in power.

The trio was later sentenced to three years each for embezzling funds meant for maintenance of presidential palaces.

The sons were released in 2015 for time served, while their father was freed last year.

Separately, Mubarak was acquitted of killing protesters during the 18-day uprising against his autocratic rule.

Australian Associated Press