After celebrating the Port Said football case verdict at their club's stadium, Ahly Ultras headed to the vicinity of the Ministry of Interior located close to Tahrir Square.
Hundreds of the hardcore football fans started protesting, demanding that security officials accused of killing members of the Ultras are held accountable.
Clashes erupted as the Ultras neared the Ministry of Interior headquarters. The police fired tear gas at the protesters.
Port Said Criminal Court handed on Saturday the death sentence to 21 defendants in a case concerning the massacre of Ahly fans at a football game in the city. Accused security officials were not part of the 21 condemned.
Seventy-three defendants, including nine security officials, three Masry Football Club officials and a number of fans, are on trial for their suspected role in Egypt's worst-ever football tragedy. More than 70 Alhy fans died in the violent attack 1 February 2012.
It is widely believed that security, both military and police, let the football massacre happen allowing Port Said's Masry team fans to storm the stadium stands of Ahly fans.
Ultras have often clashed with police during demonstrations as well as during football matches. Many Ultras members have died durnig clashes.