The father of jailed journalist Peter Geste says he hopes an Egyptian court will clear his son of spreading false news, but he’s preparing for the worst.

The parents of an Australian journalist facing the prospect of at least 15 years in an Egyptian jail are praying he’ll be acquitted, but are also preparing for the worst.

Peter Greste and two other reporters working for Qatar-based Al Jazeera English news network are among the 20 accused, in a trial that has triggered international outrage amid fears of growing media restrictions in Egypt.

Of those on trial, 16 are Egyptians charged with joining the Brotherhood, which, after the army’s ousting last July of elected president Mohamed Morsi, has been designated a “terrorist” organisation.

Four foreigners, including Greste, are charged with “spreading false news” and collaborating with and assisting the Egyptian defendants in their crimes by providing media material, as well as editing and publishing it.

This week, an Egyptian court said it would issue a verdict in a week’s time, on June 23.

That day can’t come soon enough for his Brisbane-based parents Juris and Lois Greste, who on Tuesday said they were trying to remain optimistic that their son would be acquitted.

But they’ve admitted they’re also planning for the worst, as prosecutors seek the maximum penalty of 15 to 25 years in jail for all defendants.

“Anyone with even a passing understanding of the law and legal practice would realise that if it is about the law, the only possible outcome can be a complete acquittal,” Mr Greste told ABC radio on Tuesday.

“But at the same time we are preparing ourselves for any number of other options.”

The couple said they had a phone conference booked with foreign affairs officials now a date for the verdict was known.

“We will be discussing strategies for some of the worst-case scenarios,” Mr Greste said.

Mrs Greste said her son had some sense of the international outrage surrounding the case, and that had buoyed him enormously during the six months he’d been locked up.