The United Nations has urged Egypt to release detained foreign journalists, including Australian Peter Greste, accused of airing false news.
Mr Greste, 48, and two al-Jazeera English network colleagues were arrested at a Cairo hotel on 29 December last year on suspicion of broadcasting false news in the service of the blacklisted Muslim Brotherhood.
Egyptian prosecutors have since referred to trial 20 al-Jazeera journalists, including Mr Greste, for airing false news, AAP reports.
UN High Commissioner for Human Rights spokesman Rupert Colville says the move, based on "vague charges", was of great concern.
In a statement delivered in Geneva on Friday night, Mr Colville said the prosecutors' announcement had increased fears among the general media.
"We urge the Egyptian authorities to promptly release all journalists imprisoned for carrying out legitimate news reporting activities in exercise of their fundamental human rights."
Australian Foreign Minister Julie Bishop has spoken with her Egyptian counterpart Nabil Fahmy to express her concerns about the charges, but told the ABC it was not possible for a nation to interfere in the criminal proceedings of another country.
Mr Greste, usually East Africa correspondent for the global network, was due to work in Egypt for only a short time, relieving a colleague.