An Egyptian court on Monday sentenced Alaa Abdel-Fattah, a prominent activist and a vocal critic of former Egyptian president Hosni Mubarak, to five years in prison for participating in an unauthorized protest, according to media reports.

Abdel-Fattah was faced with charges stemming from participation in a November 2013 protest rally against a controversial clause in the draft of the new constitution that permitted trial of civilians in military courts. The clause was later adopted by referendum. In June 2014, Abdel-Fattah had been sentenced to 15 years in prison, but a retrial was later ordered by the court.

Protests reportedly erupted in the courtroom after the verdict, with people shouting: "Down with oppression" and "Down with military rule!"

Defense lawyer Mohammed Abdel-Aziz criticized the verdict, calling it "harsh and oppressive," adding that the court "didn't take into consideration any of the evidence that showed the defendants' innocence," The Associated Press reported.

Defense lawyers also said that they will appeal the ruling in Egypt's Court of Cassation, the country's highest appeals court.

Under Egypt's current laws, protests without prior government permission are prohibited, a step taken after the military overthrew President Mohammed Morsi in 2013. Abdel-Fattah was prominent during the 2011 demonstrations against then-leader Mubarak and has since campaigned against military trials of civilians. He had also opposed Islamist President Mohammed Morsi.

Three other the defendants in the case received 15 years in prison for being absent from the court, while 21 others received three years in prison and were fined about $13,000.