Riots in the weeks following last month’s presidential election killed at least 800 people, according to an international human rights group.
In a report on Monday, Human Rights Watch said the victims died in rioting across 12 northern states that broke out after the main opposition candidate, Muhammadu Buhari, a northern Muslim, was defeated by incumbent Goodluck Jonathan, a Christian from southern Nigeria.
The election result prompted supporters of Buhari to hold protests that quickly degenerated in violent riots and killing sprees that displaced more than 65,000 people.
HRW urged Nigeria to “promptly” investigate the violence and prosecute the perpetrators.
“The April elections were heralded as among the fairest in Nigeria’s history, but they also were among the bloodiest,” said Corinne Dufka, senior West Africa researcher at Human Rights Watch.
“The newly elected authorities should quickly build on the democratic gains from the elections by bringing to justice those who orchestrated these horrific crimes and addressing the root causes of the violence.”
HRW based its report on 55 interviews with witnesses and victims of the violence, including Christian and Muslim clergy, and police officials.
Estimates of the number of people killed in the riots varies. The Christian Association of Nigeria said that at least 170 Christians had been killed, with hundreds more injured and some 350 churches burned or destroyed by Muslims.
Muslims and Christians interviewed by HRW put the number of dead in the largely Christian towns and villages of southern Kaduna State at more than 500. Most of the victims in this area were Muslims caught up in reprisal attacks by Christians.
In the cities of Kaduna and Zaria, in northern Kaduna State, HRW estimates that at least 180 people were killed in riots.
A lecturer at a college on the outskirts of Zaria described an attack on the college: “When you see the mob, they were not in their senses. The students ran away but the mob pursued them into the staff quarters and they had nowhere to go
“The mob beat them to death and hit them with machetes. Four Christian students and a Christian lecturer were killed.”
The violence was often only halted when soldiers were deployed to the affected areas, but HRW said that both the police and the military were implicated in the “excessive” use of force and “other serious abuses” while responding to the rioting, including eight cases of police and soldiers killing unarmed residents in Zaria and Kaduna.
“The Nigerian authorities should promptly investigate these credible reports of unlawful killings and other abuses by members of the security forces,” said Dufka.
“The use of violence by rioters, mobs and state actors alike needs to be stopped."
Sectarian violence has flared up with alarming frequency in the northern states in recent years. Last year, more than 500 people were killed in one Christian village in Jos, an area that lies along the meeting point between Nigeria’s predominantly Muslim north and Christian south.
On Christmas Eve last year, at least 38 people died across Nigeria when men linked to the radical Muslim group Boko Haram went on the rampage, attacking churches and a market in a largely Christian area.