MAIDUGURI, Nigeria - Suspected Boko Haram militants attacked Nigeria's major northeastern city of Maiduguri and the town of Monguno in the same state on Sunday, military, government and local sources said.
Sunni jihadist group Boko Haram has killed thousands during a five-year insurgency to carve out an Islamic state in the northeast of Africa's most populous country.
The army's inability to squash the group is a major headache for President Goodluck Jonathan, who is seeking re-election in February and who visited the state capital on Saturday as part of his campaign. Opposition candidate Muhammadu Buhari had been due to arrive on Monday.
The assault on Maiduguri began just after midnight and that on Monguno later in the morning. At around 9 am (0800 GMT) on Sunday, a Reuters witness in Maiduguri said shelling could be heard and that military helicopters were circling the city.
All roads have been closed, a security source said, and commercial activity has been shut down.
Nigeria's defence headquarters tweeted that coordinated land and air operations were being used to repel the attacks and a curfew had been imposed on Maiduguri.
The militants began the attack at the edge of the city in the Njimtilo area. Maiduguri is the capital of Borno state and would be a major prize for the insurgents who are trying to carve out an Islamic state.
The militants control vast swathes of Borno state and some areas of neighbouring Adamawa and Yobe states, and recently took control of the town and a multi-national army base at Baga by Lake Chad.
The government said 150 people had been killed in that attack but local officials say the figure is far higher and some have put it as high as 2,000.
Monguno is about 138 kilometres (miles) north of the state capital, and just over 50 kilometres from Baga. Security sources said the attack there began on Sunday morning and that the military was being overwhelmed by Boko Haram's firepower. Houses in the town were also being set on fire. "Boko Haram has more power than us and are shelling the town ... our colleagues are fleeing," a soldier in Maiduguri said after speaking to friends fighting the insurgents in Monguno.
US Secretary of State John Kerry is due to arrive in commercial capital Lagos, in the southwest of country, later on Sunday. Nigeria is Africa's biggest economy.
Boko Haram last attempted to take Maiduguri from the same area in December 2013, attacking a nearby army and airforce base which is also the area's civilian airport.
Security sources said the militants tried to take the airport again during the latest attack but were repelled to about 350 metres away.
A resident, Rachel Adamu, who lives around Njimtilo said"please pray for us, we are in danger, under serious attack now."