Egyptian prosecutors have demanded the “maximum” penalty for Australian journalist Peter Greste and his 19 co-defendants.
Greste was arrested in December and accused of defaming Egypt and having ties to the blacklisted Muslim Brotherhood.
Five other Al Jazeera journalists, including the broadcaster’s English channel Cairo bureau chief Mohamed Fahmy and producer Baher Mohamed, are also facing trial.
The trio could be jailed for 15 years, according to defence lawyer Ibrahim Abdel Wahab.
The other defendants in the case – Egyptians who have been charged with joining the Brotherhood – could get prison terms of 25 years.
Most of the defendants are being tried in absentia.
The trial comes against the backdrop of strained relations between Cairo and Qatar, which supports the Muslim Brotherhood movement of deposed Islamist president Mohammed Morsi.
It has sparked an international outcry and calls for the release of the journalists, while Cairo insists the trial does not presage a wider crackdown on journalists.
Al Jazeera is taking separate legal action against Egypt in an international tribunal.
The media company is seeking $US150 million in compensation from Egypt for the mistreatment of Al Jazeera journalists, including Greste, the jamming of Al Jazeera satellites broadcasting in Egypt and the closure of Al Jazeera’s bureau in Cairo.