Human Rights Watch has urged the Egyptian authorities to bring to justice those responsible for recent sectarian violence, a report on its official page said on Wednesday.

At least two people were killed when violent clashes broke out outside Saint Mark’s Coptic Cathedral on Sunday during a funeral for four Christians who were killed in sectarian violence over the weekend in a town northeast of Cairo.

Violent confrontations in the Khusus town, which left four Christians and one Muslim dead, according to official numbers, had raised concerns about the Islamist-ruled most populous Arab country.

The New York-based non-governmental organization also urged Egypt to investigate what it described as the police's failure to act effectively to contain the violence.

HRW’s Middle East and North Africa deputy, Nadim Houry, called on President Mohamed Mursi “to acknowledge the deep and longstanding problem of sectarian violence in Egypt and take decisive steps to address it before it escalates further.”

Houry argued that many similar incidents have been left unpunished in the past, asking him to “break the cycle of impunity” and reform the law as to grant Christians an equal right to worship.

“Egyptian law discriminates against Christians by prohibiting the renovation or construction of churches without a presidential decree, a requirement which is not applied to other religions and their places of worship.”

The NGO argued that the above mentioned point has been the source of tension between the two communities, asking the government to make that its legislature’s priority.

The report accused Egypt’s Islamist president of not taking serious steps towards investigating sectarian violence cases that took place under his administration or its predecessor, the military council, or under toppled autocrat Hosni Mubarak.