A Boko Haram spokesman has given Christians a three-day ultimatum to leave the Muslim north [AFP]

Boko Haram is a radical Islamist group blamed for a spate of recent attacks on Christians in Nigeria.

The group was founded in 2002 in Maiduguri, the capital of Borno state, allegedly by Mohammed Yusuf, a religious teacher.

In 2004, it moved to Kanamma in Yobe state, close to the border with Niger, where it set up a base dubbed "Afghanistan", from which it attacked nearby police outposts.

Boko Haram means "Western education is sin" in the Hausa language spoken in Nigeria's north. It is believed to have a number of factions with differing aims, including some with political links.

The group initially claimed to be fighting for the creation of an Islamic state in the north, but a range of demands by different people have since been issued.

Recent attacks

Abul Qaqae, who has presented himself numerous times as a Boko Haram spokesman, on Sunday issued a three-day ultimatum for Christians to leave the mainly Muslim north. He has since claimed the group is behind attacks on church worshippers and Christian mourners this week.

The lates violence has left scores of people dead [Reuters]

Criminal gangs are also believed to have carried out violence under the guise of Boko Haram. Conspiracy theories abound as well, including whether enemies of President Goodluck Jonathan, a southern Christian who faces strong opposition in the north, have backed the violence.

Its first real leader was the late Mohammed Yusuf, who convinced young people to join him despite having only elementary knowledge of the Koran, according to one professor who has studied the group.

His former deputy Abubakar Shekau is widely believed to currently lead Boko Haram's main Islamist cell, which says it wants to be known by a different name, roughly translated as "People Committed to the Prophet's Teachings for Propagation and Jihad".

Boko Haram launched an uprising in 2009, leading to nearly a week of fighting that ended with a military assault which left some 800 dead and the group's mosque and headquarters in northeastern Maiduguri in ruins.

Yusuf was captured and later killed when police said he was trying to escape from custody - but his body was found in the street, still handcuffed, raising concerns that he had been the victim of an extrajudicial killing.

Motivation questioned

Boko Haram went dormant for more than a year before re-emerging in 2010 with a series of assassinations. Bomb blasts, including suicide attacks, have since become frequent and increasingly deadly.

Salisu Mohammed, a conflict management specialist, told Al Jazeera that Nigerian authorities should have acted sooner to stop the proliferation of Boko Haram.

"Many people have known of the existence of this group, silently and within the community, especially in the last year," he said.

"They are becoming more extreme because in the past there wasn't a major push in place to check their proliferation.

"They are taking advantage of a broken-down structural condition in Nigeria that people can take the law into their hands without getting reprimanded."

Analysts have also said that at the heart of this week's violence is dire poverty and political manoeuvring - not religion.

They believe attacks were committed mainly by frustrated, unemployed youths and orchestrated by religious leaders and politicians who manipulate them to retain power.