CAIRO (AP) - A 17-year-old boy sought to protect a girl from being sexually harassed by three youths. But he ended up being killed by the three teens who stabbed him repeatedly.

On Sunday (Dec 22), a court in Egypt convicted the three teenage boys and sentenced them to 15 years in prison.

The juvenile court in the Nile Delta region found the three defendants had repeatedly stabbed Mahmoud el-Banna, 17, during the confrontation in October. The court also sentenced a fourth defendant to five years in prison for his role in driving the assailants to the scene of crime. The verdict can be appealed before a higher court.

El-Banna's killing stunned Egypt, with local media extensively covering the case. Surveys indicate that a vast majority of Egyptian women feel insecure in the streets.

There were calls on social media to execute the defendants, who are all under 18 years of age. The court gave them the maximum sentence set by Egypt's laws for children accused of murder.

Sunday's session took place amid tight security because of a fear of protests in the Nile Delta city of Shebeen el-Kom, 75km north of the capital, Cairo.

During a previous session in October, police arrested at least two dozen people who protested outside the court. Egypt's government has effectively banned all public protests since 2013.

Egypt's Interior Ministry said at the time that all those arrested were members of the banned Muslim Brotherhood group and were inciting riots. Sexual harassment, mostly ranging from catcalls to occasional pinching or grabbing, is rampant in Egypt.

In 2014, Egypt's penal code was amended amid pressure from women's groups to include a broad definition of sexual harassment and tougher penalties. However, most women remain reluctant to file complaints for fear of stigmatisation.