A young inventor has spoken about his disappointment at being barred from representing Egypt an international science competition.

Abdallah Assem, 17, was prevented from boarding a flight at Cairo Airport on Sunday.

He was scheduled to represent Egypt at the Intel International Science and Engineering Fair (Intel ISEF) in Los Angeles.

Assem was arrested on 24 April in Cairo's Bab El-Louk district on charges of illegal protesting and participating in the burning of a police vehicle. He was later released on bail pending trial.

He denied the charges in comments to Al-Ahram Arabic news website.

He said he was innocently walking through the area, in which a pro-Mohamed Morsi protest was taking place, carrying his science equipment.  

"I don't know why this happening to me. I was only travelling for six days. I don't know what danger I pose to Egyptian national security," Assem said.

Assem is senior in high school in Aswan, Upper Egypt. His research focused on quadriplegic patients.

A law, passed in November, bans protests without prior approval by the police. Thousands of Morsi supporters as well as liberals have been arrested for defying the law.