The militant Islamist group known as Boko Haram has claimed responsibility for a suicide bombing that killed at least 15 people in northern Nigeria.

In a statement e-mailed to journalists Monday, group spokesman Abul Qaqa said Boko Haram had “successfully launched” an attack at a church in the city of Bauchi.

A suicide bomber drove a car packed with explosives into the church Sunday, causing the building to collapse and trapping worshipers inside. More than 40 people were injured in addition to those killed.

Boko Haram has bombed churches before, including one near the capital, Abuja, last Christmas. That attack killed more than 30 people.

The statement from Qaqa accused Nigeria's security agencies of concealing casualties in their battles with the militant group. He also warned the group will attack journalists who, in Boko Haram's view, are favoring the security agencies in their reporting.

There was no way to confirm the authenticity of the statement.

The militants are blamed for hundreds of killings in Nigeria, mostly in the north, since 2009. The group says it wants to establish an Islamic state in northern Nigeria and does not recognize the government or the country's constitution.

The country of 150 million is about evenly divided between Muslims, who live mostly in the north, and Christians who dominate the south.