The death toll from a bomb attack on a church just outside Nigeria's capital Abuja on Christmas Day has risen to 37, with 57 people wounded, a source at the National Emergency Management Agency (NEMA) said on Friday.

The bombing at St. Theresa's Catholic church in Madalla on Abuja's outskirts during a packed Christmas mass, was the deadliest of a series of Christmas attacks on Nigerian churches and other targets by the militant Islamist sect Boko Haram.

As of just now, the latest death toll from the bombing of St. Theresa's church is at 37. Wounded, we have 57, a senior NEMA official said. The initial death toll had been 27.

The official asked not to be identified because the victims were now in the hands of hospitals and morgues.

President Goodluck Jonathan summoned his security chiefs for an emergency meeting Thursday to discuss the growing Islamist militant threat and how to deal with it.

This year was the second in a row that Boko Haram has attacked churches at Christmas. Its strikes are becoming deadlier and more sophisticated, and have raised fears that the militants are trying to ignite sectarian strife in country historically prone to conflicts between a largely Muslim north and Christian south.

Boko Haram, whose name means Western education is sinful in the northern Hausa language, has been blamed for a campaign of shootings and bombings against security forces and authorities in the north.

Attacks in and around the capital - including one on the U.N. headquarters in August that killed at least 24 people - suggest the group is trying to raise its profile and radiate out from its heartland in the northeast.

Tuesday night, unidentified attackers threw a homemade bomb into an Islamic school in Nigeria's southern Delta state, in an apparent sectarian reprisal that wounded seven people, six of them young children.

Wednesday night, an explosion in a local bar in the northern city of Gombe wounded one person, police said.

(Reporting by Tim Cocks; Editing by Peter Graff)