The court had already put off its much anticipated verdict last Thursday because the presiding judge Hassan Farid was reportedly ill.
Another judge today said the verdict was again delayed because other defendants in the trial could not be brought to the court from their cells.
Australian Peter Greste, Canadian Mohamed Fahmy and Egyptian Baher Mohamed were jailed last year for "spreading false news" in support of the blacklisted Muslim Brotherhood during coverage of the turmoil after the army ousted Islamist president Mohamed Morsi in 2013.
While Greste has since been deported, Fahmy, Baher and several other defendants were released on bail at the start of the retrial. But at least three other defendants have been jailed in separate cases.
Also Read
"Verdict postponed until August 29th. The audacity & continuous disrespect to our rights is unprecedented!" Fahmy tweeted after Sunday's postponement.
Defence lawyer Shaaban Said said there was no political reason for postponing the verdict.
"The (presiding) judge is ill and he cannot come. Legally the verdict cannot be delivered by a new judge," he said.
"It's a long-running saga, it just seems to keep going on and on and on," Giles Trendle, Al-Jazeera English managing director told AFP. The three all worked for the English channel.
"We are exasperated, frustrated. We just want justice to be done and justice keeps getting delayed. Justice delayed is not justice done."
Producer Mohamed said the postponement was yet another insult to the three.
"It's really annoying that my life is still on hold... It will be another month of suffering," he told reporters.
"I fear a guilty verdict."
The case has deeply embarrassed President Abdel Fattah al-Sisi, who has said he wishes the reporters had never gone on trial.
"He rejected calls to intervene while the retrial was pending, but it will be over when the verdict is announced.