Four rights organisations, including Human Rights Watch (HRW), say Egyptian officials are "turning a blind eye" to police abuses in Port Said.
HRW published a report Saturday saying that it has, along with the Cairo Institute for Human Rights Studies, the Egyptian Initiative for Personal Rights (EIPR) and Al-Karama Foundation, gathered evidence incriminating the police.
They called on the newly-appointed investigative judge, Abdel Aziz Shaheen, looking into January's violence in Port Said to "fully examine police responsibility for the unlawful killings."
"Evidence gathered... indicates that the police began shooting when they came under fire on January 26, but continued shooting after the threat against them receded, killing and wounding a number of protesters and bystanders," the report said.
"The police also used lethal fire on the following two days, when the threat to life was unclear at best," it added.
According to the report, since Justice Minister Ahmed Mekki appointed Shaheen on 18 February to investigate the issue, "no charges have been brought against any police officer."
Sarah Leah Whitson, Middle East director at HRW, said that Egypt's President Mohamed Morsi should order the police to limit its use of force to "strictly necessary" situations.
"[Morsi] should publicly acknowledge that the police's right to use lethal force is not unlimited, even when they come under attack," she said.
Whitson also criticised the "lack of police reform... [and] lack of accountability" which give the police "a free hand to use lethal force" like it did during ousted president Hosni Mubarak's rule.
The organisations put forward a number of recommendations to tackle the issue, including amending Article 102 of the 1971 Police Law number 109 "to limit the use of lethal force to cases of self-defence or the defence of others against the imminent threat of death... [or] to prevent a particularly serious crime."
They also recommended repealing "the interior ministry decree 156/1964, which permits the use of live ammunition to disperse demonstrations, and replace it with a decree that complies with international standards for maintaining security."
In addition, they demanded that Shaheen conduct an independent investigation into the violence in Port Said and ensure that those implicated are prosecuted before a judge.
The HRW report details day-by-day events in Port Said when deadly clashes and riots erupted after a court gave a death sentence to 21 Port Said residents on 26 January on charges of murder at an Ahly v Masry football match a year earlier in the city.
The two-year anniversary of the Egyptian revolution was just the day before the judgment was announced. Between that and the police-protester clashes that went on for several days after the judgment about 42 people were killed in the city.
HRW did not fully accept the interior ministry's take on the clashes.
"The picture that emerged suggests that up to seven unidentified men opened fire on police outside the Port Said prison... shortly after [announcing the verdict]... The gunmen, some of whom used automatic weapons, killed two police officers and wounded 10 others in what the Interior Ministry claimed was an aborted prison break," the statement reads.
HRW said that the interior ministry did not provide enough evidence to support this scenario, emphasising that police "shot live ammunition" from the prison roof and on the ground and have continued to do so even after they were no longer being attacked.
It is expected that the verdict against the rest of the 73 defendants, including senior police officials, in the 2011 Port Said football massacre will be announced on 9 March.