At least 1,200 people have been killed in the last four years in Northern Nigeria by the militant Islamist group Boko Haram, according to a preliminary investigation by the International Criminal Court.

The Court’s chief prosecutor, Fatou Bensouda, said on Monday (August 5) the ICC is investigating Boko Haram for “crimes against humanity” through “widespread and systematic attacks”, the scale and intensity of which have increased over time.

The initial ICC report is based on statistics leading up to December 2012. The ICC is now considering whether it merits further investigation.

The International Criminal Court, based in The Hague, tries cases of crimes against humanity, war crimes, and genocide when a country’s own courts fail to prosecute. Nigeria agreed in 2001 to subject itself to the jurisdiction of the ICC.

Pastor Ayo Oritsejafor, president of the Christian Association of Nigeria, agreed that the rate of attacks is intensifying.

In a recent speech, he said: “In my first term, about 3000 Christians were killed. Last year alone averaged over 100 every month. In March 2010, about 500 Christians were slaughtered in one night on an attack on their villages. In April 2011, our members lost over 500 churches, thousands of homes and businesses in a 48 hour period, and in 2012 about 70 per cent of all Christians killed worldwide were in northern Nigeria alone.”

Oritsejafor added that he doubted Boko Haram were ready for constructive dialogue and called upon Nigeria’s Islamic leaders to condemn recent attacks and redress misinterpretations of the Qu’ran.

“The real Islam that CAN knows [about] should make true leaders of the faith to rectify the contradictions of arbitrary knowledge of the Qur’an to remind those pushed out of the line to seek the good of all,” he said.

Boko Haram, which among other demands wants the imposition of Sharia law in Nigeria, has claimed responsibility for many of the attacks across the country.

Despite the imposition of a curfew and a declaration of a “state of emergency” by the federal government in affected states, Boko Haram and affiliated terrorist groups have continued their attacks, especially in the north-eastern states of Borno, Yobe and Kano.

Boko Haram has also rejected a proposed ceasefire by the Nigerian government. Bensouda said the ICC is considering whether the government has done enough to prevent the attacks and to bring the perpetrators to justice.

World Watch Monitor reported last week that at least twelve people were killed in a bomb blast in the Christian-dominated Sabon Geri area of Kano on July 29. The death count has now been doubled.

At least 20 people were killed on July 27 in an attack in the northeastern state of Borno. Boko Haram is suspected to have carried out both attacks.

In response, some of Borno’s youths have joined together to form a vigilante group to thwart attacks, while the establishment of a similar group has been proposed in Kano state, in Nigeria’s north.

Tobias Idika, president of community group Ohanaeze Ndi-Igbo in Kano, told World Watch Monitor a vigilante group would guard areas especially likely to be targeted by terrorists, such as public spaces and places of worship.

“We are fine-tuning the arrangement and reaching out to all stakeholders and the government to stop the endless blood-letting,” he said. “The vigilante will include professionals and will work with other security agents. Our goal is to protect the people within the ambit of the law,” Idiaka said.

He said the vigilante group would work in conjunction with the police, carrying weapons approved by the police and providing them with intelligence.

The intervention of the Borno Vigilance Youth Group, which carries sticks and knives but not guns, in preventing attacks by Boko Haram has been hailed by both the state government and tribal leaders.

Governor Kashim Shettima, who said the military task force and police support the youth initiative, said it is “divine intervention in bringing an end to the incessant massive attacks and killing in the state”.

Tribal leader Abubakar El-Kanemi, the ‘Shehu’ (meaning sultan) of Borno, also praised the efforts of the youths, but cautioned them not to take the law into their hands.

Bishop Ransom Bello, chairman of the Kano chapter of CAN, said the formation of the community vigilante group will be a positive development, but that they should not carry guns.

“What we are against is arming them with guns and ammunition,” Bello said. “As Christians, we don’t believe in retaliatory attacks or any form of violence. The truth is that what we have is not a case of the Muslims fighting Christians. It is an Islamic group that is fighting everybody. We are doing our best to educate the people to be vigilant, keep praying and be patient as we all collaborate to ward off the attackers.”

Thousands of people are fleeing north-eastern Nigeria. In June, the United Nations High Commissioner for Refugees reported that more than 6,000 have left for neighbouring Niger.