At least 40 people were killed in attacks targeting Christians in Nigerian churches in northern and central areas on Christmas Day. Islamist group Boko Haram owned up to the attacks but denies reports that it has links to al-Qaeda.

This group, founded in 2002 by Ustaz Mohammed Yusuf, is a controversial militant Islamist group that intends to impose Shariah law in Northern Nigeria. The name Boko Haram itself literally means "Western education forbidden."

Since then, some 90,000 people have fled their homes amid conflicts between Boko Haram and police in Damaturu, a local government area in northern Nigeria.

In a speech at St. Theresa Church outside the capital city of Abuja, Pastor Ayo Oritsejafor, president of the Christian Association of Nigeria, said the attacks were "deemed as a declaration of war on Christians and Nigeria as an entity," and that though he did not want to encourage acts of revenge, "Christians should protect themselves in any way they can."

Nigerian President Goodluck Jonathan, who is a Christian, has held urgent meetings with Muslim and Christian leaders in an attempt to restore peace.

Muslim leaders have moved to downplay the prospect of communal clashes.

On Tuesday, December 27, Nigeria's main Muslim cleric, Muhammad Sa'ad Abubakar, condemned the Christmas Day attacks and called for calm.

In a related event, this group was also responsible for a series of bomb explosions in the central city of Jos on Christmas Eve 2010.