Egypt's highest appeals court has upheld a five-year prison sentence for Alaa Abdel-Fattah, an iconic figure of the country's pro-democracy movement convicted for taking part in a peaceful demonstration in 2013.

Judge Hani Mustafa pronounced the decision on Wednesday, upholding a prior verdict by a criminal court that ruled Abdel-Fattah had protested illegally, endangered the public interest, and stole a police radio.

Street protests have been effectively banned in Egypt.

Abdel-Fattah's aunt Ahdaf Soueif, a novelist and rights advocate, lamented the decision.

She says: "I'm sorry. Our hearts are with everyone who's been following us and rooting for Alaa and justice. We stay together."

Abdel-Fattah has around a year-and-a-half remaining in his sentence. He also faces another sentencing in December over accusations he insulted the judiciary.