CAIRO (AFP) - A Cairo court Thursday sentenced two men to life in prison for sexual attacks, in the latest example of the authorities' growing determination to tackle an epidemic of such crimes.

Egypt has been roiled by sexual violence since the 2011 uprising that toppled Hosni Mubarak, with women regularly attacked by mobs at rallies in and around Cairo's Tahrir Square - the focus of demonstrations.

Thirteen men were arrested for sexual attacks that took place on June 3 and 8 as revellers celebrated Abdel Fattah al-Sisi's presidential victory, and on January 25, 2013 when Egypt marked the second anniversary of the anti-Mubarak revolt.

They were arrested amid an outcry after a graphic video of a woman being sexually assaulted at Tahrir Square went viral on social networks in early June.

Seven of the 13 defendants were sentenced on July 16 to life in prison, while two others received 20 years in jail in these cases.

On Thursday, two men were handed life imprisonment, while a minor was jailed for 20 years in the same cases. The fate of the fourth defendant was still unclear.

Life sentences in Egypt run 25 years.

The 13 accused were charged with kidnapping, rape, sexual attacks and attempting to murder and torture a mother and her daughter, the prosecution said previously.

Lawyer Ahmed Mesilhy from Cairo's Lawyers Syndicate who specialises in cases involving minors told AFP that the verdict issued against the minor was "against the children's law".

"The maximum sentence for children is 15 years according to the (Egyptian) law ... punishment for children should be with the purpose of rehabilitation not vengeance," he said, adding that his group planned to get a stay order on the verdict.

Activists have repeatedly accused the government of turning a blind eye to the country's rampant phenomenon of sexual violence.

Between November 2012 and June 2013, around 250 cases of sexual assault or harassment by mobs or rapes using weapons were reported during protests in Cairo, according to activists.

Egypt's government, which had no specific law on sexual harassment, only recently approved penalties for such offences of jail terms, fines or both, vowing to tackle the rise in these crimes.

Sisi was sworn in as president on June 8, nearly a year after he ousted his predecessor Mohamed Mursi, Egypt's first freely elected leader.