Nigeria’s military has repelled a new attack by militant Islamist group Boko Haram on the strategically important north-eastern city of Maiduguri, an army source has told the BBC.
Dozens of militants and soldiers were reportedly killed during a major assault on the city on Sunday.
The city is quiet on Monday, with some businesses open, a BBC reporter says.
Earlier on Sunday, Boko Haram captured the north-eastern town of Monguno – the latest to be seized by the group.
It launched an insurgency in north-eastern Nigeria in 2009 to create an Islamic state.
US Secretary of State John Kerry arrived in Nigeria on Sunday to call for peaceful elections next month.
Nigeria correspondent Will Ross says that Mr Kerry is in Nigeria to show solidarity in the fight against Boko Haram.
Government troops beat back Boko Haram fighters after they launched an assault on Maiduguri on Sunday night – the second in less than 24 hours, an army source said.
Both attacks were in the Jimtilo district.
Loud explosions were heard in the city, a resident told the BBC Hausa service.
A 24-hour curfew was imposed on Sunday but this has since been relaxed.
Our correspondent says the militants have captured so much territory surrounding Maiduguri that there is only one road in and out which is considered safe.
He says there is still a great danger that Boko Haram will return to try again.