Egypt's prosecution has arrested 21 Zamalek fans after at least 20 people died and a further dozen were injured trying to get in to a league football game between Zamalek and ENPPI at a Cairo stadium on Sunday.

The interior ministry has said that hardcore Zamalek fans, the Ultras White Knights, tried to enter the stadium by force, and had to be dispersed with teargas, while the UWK say that they were teargassed as many fans scrambled to get in, with a "tiny metal fence surrounded by barbed wire" being the only gate opened for them.

The prosecution issued the arrest order on charges of assembly, inciting violence, rioting, assaulting police officers and damaging public and private properties.

Out of the 21 arrested, 17 were arrested at the stadium on Sunday. The other four defendants are UKW leaders who were arrested from their homes on Tuesday.

Late on Tuesday the prosecution has released on bail 18 of the arrested while the other remain detained pending trial.

The violence was the deadliest football-related disaster since the infamous death of over 70 Ahly fans in the Port Said stadium in February 2012.

Authorities have ordered a probe into the deaths, in response to outrage from Zamalek fans and family members of the deceased over what they have called a "massacre".