Thirteen people were killed on Tuesday in a suicide attack at a busy cattle market in the northeastern Nigerian city of Maiduguri, the Red Cross and civilian vigilantes battling Boko Haram said.

The blast in the Borno state capital happened at about 1:00 pm (1200 GMT) as traders were wrapping up business for the day, Shettima Bulama said in an account backed up by another local vigilante.

A suicide bomber killed at least nine people on Saturday inside a mosque in northeast Nigeria's city of Maiduguri, with the blast leaving much of the building destroyed, witnesses said.

"It was suicide attack by a bomber who pretended to be worshiper," said Haruna Dawud, a trader at the Monday Market which is next to the mosque.

Nigeria's military on Saturday repelled a Boko Haram attack on the key northeastern city of Maiduguri, a day after President Muhammadu Buhari took office vowing to crush the group, witnesses and security sources said.

The overnight attack on the Borno state capital saw rocket-propelled grenades fired into homes in a bombardment that reportedly lasted several hours.

Nigerian soldiers on Saturday detonated two homemade bombs found in a camp housing people displaced by Boko Haram violence in the restive northeastern city of Maiduguri, witnesses told AFP.

Two men suspected of planting the explosives were arrested and an investigation is ongoing, they said.

Seven people were killed in a suspected suicide bomb attack at a market in the northeast Nigerian city of Maiduguri on Tuesday, police said.

"Seven persons died while 17 others were injured. The rescue is still ongoing," Borno state police commissioner Clement Adoda told reporters.

Three bombings, including one by a female suicide attacker, killed at least 58 people and wounded 139 others in northeast Nigeria on Saturday, in the latest violence blamed on Boko Haram.

Many children were among the dead in the explosions that hit two crowded markets and a busy bus station in Maiduguri, the region's largest city and capital of the embattled Borno state.

Nigeria on Monday braced for fresh Boko Haram attacks ahead of this month's elections, with the key city of Maiduguri in the firing line and forces from Chad and Cameroon joining the regional fight.

A weekend of violence saw the Borno state capital, Maiduguri, hit for the second Sunday in a row, but Nigerian Army soldiers, helped by civilian vigilantes, managed to keep the militants at bay.

Boko Haram fighters on Sunday launched a fresh attempt to take over the strategically crucial northeastern Nigerian city of Maiduguri, a brazen attack on a state capital just two weeks before national elections.

Four residents told AFP that Sunday’s fighting began at roughly 3:00 am (0200 GMT) with loud explosions and gunfire, as the Islamists tried to enter the city from the south.

Thousands of people fleeing the latest Boko Haram violence have poured into the embattled Nigerian city of Maiduguri, putting pressure on camps for the displaced as rescue workers try to cope with the influx.

A group of 5,000 people, most of them women and children, reached the Borno state capital on Monday after escaping the Islamists' weekend takeover of the nearby town of Monguno, officials said.

A city-wide curfew was lifted Monday in Maiduguri, northeast Nigeria, following a weekend Boko Haram attack that prompted the state governor to urge residents to stay and fight any future assaults.

The restive capital of Borno State was locked down on Sunday morning, after the Islamist militants launched a dawn raid that was later repelled by the military.