Ms Bishop said on Wednesday she was working with Egyptian authorities after Mr Greste and his two Al Jazeera colleagues Mohaned Fahmy and Baher Mohamed were again denied bail after their sixth appearance in court.

'I'm disappointed with the outcome of the latest hearing," she said.

"I'm continuing to raise this matter with Egyptian authorities and other governments at every opportunity."

The comments followed a farcical day in the Egyptian court where inaudible tapes and recordings were presented as key pieces of evidence by the prosecution.

Mr Greste described the presentations as "meaningless", among them a video of Greste interviewing a sheep farmer.

Distorted recordings inaudible even to the trial's judge Mohamed Nagy Shehata and footage taken before Canadian-Egyptian bureau chief Fahmy joined Al Jazeera English were also among the package of material shown to the court.

Mr Greste's brother, Andrew Greste, said on Wednesday the quality of the material was so poor there were few in the court room who could understand it.

He said the trial was becoming more difficult for the journalists and their families, but he was hopeful that with each day that revealed no incriminating evidence his brother was moving closer to exoneration.

"It gets more and more difficult, you know, the further we get down the track," he told ABC radio.

"But I guess, you know, I'd like to think and I'm hoping and praying that we're closer to a conclusion than we were at the start.

"And the thing that gives me confidence is that we haven't seen anything at all that's incriminating evidence against Peter. So I guess I'm just hopeful that we're going to eventually get to a point that, you know, he's exonerated."

Greste and his colleagues deny any wrongdoing in the trial, in which prosecutors allege the journalists and their Egyptian collaborators colluded with the Brotherhood movement of ousted president Mohamed Mursi and falsely sought to portray Egypt as being in a state of ‘‘civil war’’ since his overthrow by the army last July.

The case is seen around the world as an attack on working journalists and press freedom.

“The case turns to be an abuse against journalism and freedom of speech,’’ Greste told AFP during a recess on Tuesday.

Journalists were also ordered from the court room for a short time during Tuesday's hearing.

The three defendants became angry as the prosecution showed clip after clip of material they said was meaningless to the case.

with AFP