Human Rights Watch says the dismissal by Egypt's president of the country's top anti-graft official and his subsequent conviction for "disseminating false news" violated free speech and set a dangerous precedent.

Hesham Genena was convicted last month over a report he issued claiming that corruption has cost Egypt 600 billion pounds ($67.6 billion).

A pro-government daily quoted him in December as saying the figure referred to money lost in 2015, but Genena later said he was misquoted and that it covered four years. President Abdel-Fattah el-Sissi fired him in March after an investigation concluded he had misled the public.

HRW's Nadim Houry says in a statement released on Tuesday that Egypt has heightened abuse of free speech "to the point of turning a misunderstanding into criminal charges punishable by prison."