A Cairo University professor was detained in a Cairo police station for several hours Saturday night over t-shirts worn by university students suspected of having carried the famous pro-Morsi "Rabaa sign".

Political science professor Heba Raouf was apprehended with a number of students in Cairo's historic Citadel during an event for Egyptian Volunteer Day, where several NGOs and a student group from Cairo University were participating.

Raouf was invited to give a speech on the importance of volunteer work in the event organised by the 100 Days Project and Belange NGOs.

The design of t-shirts worn by the student group Sencro, which advocates child rights and who participated in the event, included a yellow hand that police said was the Rabaa sign.

The t-shirt print, images of which circulated online, showed many hands of different colours with palms open, unlike the Rabaa sign which exhibits four fingers and a folded thumb. The students failed to convince security personnel that the yellow palm wasn't related to Rabaa.

The event was consequently halted by security and the students, and Raouf — who is the supervisor of Sencro at the university — was taken inside a police office at the Citadel for questioning, according to 100 Days Project general coordinator Kareem Abdallah.

He said Raouf explained to the officers the design was created before the 2011 revolution and had no political connotation, but rather shows the palms of children in different colours. Security officials remained unconvinced.

The Rabaa sign represents resistance to, and memory of, the violent dispersal of a sit-in in support of ousted Islamist president Mohamed Morsi in 2013. The sign is considered by Egyptian security forces as a symbol of incitement against the army and police. A woman was sentenced to two years in prison in February for wearing a Rabaa broach.

During questioning, four members of the event from different groups were arrested randomly outside the Citadel and, along with Raouf, taken to Al-Khalifa Police Station nearby for further investigation. They were released hours later with no charges pressed, Abdallah said.

Harassment by security

Abdallah told Ahram Online that security personnel were constraining activities at the event from the beginning.

"Despite having clearance for the attendance of a range of 500 and 1,000 participants, security told us on the event day that only 300 were allowed," Abdallah said.

"They then went on to tell us and members of the Resala charity to take off t-shirts carrying the charity's logo, otherwise they'll arrest them. So having their safety in mind we told them to hide their t-shirts. Then they told us to tell everyone with a logo of their group to take them off, which we told them is impossible," he recounted in disbelief.

Abdallah said at one point security personnel said they would arrest the Resala members. "Again, afraid for their safety, we asked them to leave."

"Many of the participants in the event were students. One particular group's members were chiefly secondary school students and college freshmen who were excited about volunteer work and development. The message they got was the opposite of their aspirations; that it may be better to leave this country instead," Abdallah lamented.