Alaa Abdel Fattah, one of the most prominent voices of Egypt's 2011 revolution, has been sentenced to five years in prison for violating a protest law deemed "draconian" by rights groups.

He was sentenced alongside more than a dozen other activists and a student linked to a protest against a constitutional reform that would allow civilians to be tried in military courts in November 2013.

Abdel Fattah's case was closely followed by the activists and revolutionaries who first led calls for the removal of then President Hosni Mubarak four years ago. A blogger and activist, he became one of the leading figures of the revolution and a guiding voice in the turmoil of the years that followed.

Abdel Fattah was sentenced at a retrial on Monday for 25 defendants arrested for the protest, which took place outside Egypt's upper house of parliament.

Eighteen of the defendants received three-year sentences, while a further four were given 15-year terms in absentia.