The continued detention of photojournalist Mahmoud “Shawkan” Abu Zeid “exposes the rank hypocrisy” behind Egypt's claim to uphold press freedom, Amnesty International said in a Thursday statement.

The UK-based rights group has collected over 90,000 signatures worldwide in a petition supporting their call for the immediate release of Shawkan, who has been detained for over 849 days.

Amnesty describes Shawkan as a "prisoner of conscience," and say he has been denied essential medical treatment for Hepatitis C.

The 28-year-old photojournalist was arrested in August 2013 while covering the violent dispersal of Mohamed Morsi supporters at the Rabaa sit-in in Cairo.

Prosecutors have repeatedly renewed the pre-trial detention of Shawkan and others detained in the same case since their arrest, with no trial. However, a trial has been scheduled to start on 12 December.

Earlier in December, Amnesty released a letter from Shawkan, written in jail, thanking his supporters for standing by him and adding: “keep shouting, journalism is not a crime.”

In a previous letter, Shawkan wrote that he was “neither a supporter nor an opponent of anyone. I don't care about anything except my professional work as a photojournalist.”

Last December, the Committee to Protect Journalists (CPJ) ranked Egypt as among the worst ten jailers of journalists in the year 2014.

The Egyptian government has repeatedly denied it imprisons journalists or reporters for their work, arguing that all those jailed have been charged with or convicted of crimes.