One year after a massive attack ranked among the worst in Boko Haram's six-year insurgency, the residents of Baga in northeast Nigeria say their home is a ghost town.

The jihadists razed the fishing hub on the shores of Lake Chad in a four-day assault beginning January 3 last year, forcing thousands from their homes and killing hundreds of others.

Nigeria's information minister on Tuesday insisted that Boko Haram was "largely defeated" despite two days of bombings blamed on the jihadist group that left dozens dead in the volatile northeast.

Lai Mohammed maintained the Nigerian government had greatly reduced the group's capacity to attack and was on its last week.

Two female suicide bombers struck a market in the northeast Nigerian state of Adamawa on Monday, an army official said, with a local community leader giving a toll of at least 30 killed.

The military chief in Adamawa state, Brigadier-General Victor Ezugwu, confirmed the twin suicide blasts in the town of Madagali but did not give a toll.

Boko Haram jihadists attacked a key city in northeast Nigeria on Sunday evening, residents told AFP, the second assault in days as Nigerian President Muhammadu Buhari's deadline to eradicate the militants is set to expire.

The jihadists invaded Jiddari Polo, an area on the outskirts of the capital of northeastern Borno state, Maiduguri, at around 6:30 pm (1730 GMT), shooting guns and unleashing explosives.

At least 14 people were killed and several others injured by Boko Haram gunmen in a Christmas Day attack on a village in northeastern Nigeria, vigilantes said Saturday.

Attacking astride bicycles, the jihadists invaded Kimba village in flashpoint Borno state around 10:00 pm on Friday, opening fire on residents and torching their homes.

President Muhammadu Buhari said Nigeria has "technically" won the war against Boko Haram though suicide bombers remain a threat, in remarks issued days before his self-imposed deadline to defeat the jihadist group expires.

In the remarks, the leader of Africa's most populous country worked to reassure Nigerians that the jihadists now were unable to mount effective "conventional attacks" in the country's volatile north.

The Boko Haram insurgency has kept more than one million children out of school, the U.N. children's agency reported on Tuesday, highlighting fears that a lack of education will fuel further radicalism in and around Nigeria.

Over 2,000 schools are closed across Nigeria, Cameroon, Chad and Niger, while hundreds of others have been attacked, looted, or set on fire by Boko Haram jihadists in their quest to create an independent Islamic state, said UNICEF.

A child suicide bomber detonated his explosives, killing himself, two other bombers and six people in Nigeria's northeast, in the latest bloodshed blamed on Boko Haram Islamist group, the army said on Monday.

The attack in Beninsheikh in Borno state happened around 8.30 pm on Sunday when three suspected suicide bombers aged between 10 and 15 years, were stopped for security screening by civilian vigilantes in the area, Colonel Sani Usman said in a statement.

Nigerian troops have killed 12 Boko Haram fighters and recovered a cache of arms and ammunition from the hardline Islamist group whose six-year insurgency has claimed thousands of lives, a military spokesman said.

"As part of their determined efforts to rid the society of all known Boko Haram terrorists enclaves and hideouts, troops... conducted a fighting patrol along Damboa-Njaba-Bale road in Borno state" in the northeast of the country, Colonel Sani Usman said in a statement late Sunday.

Boko Haram gunmen launched a dawn raid Saturday on the hometown of Nigeria's army chief, triggering a fierce gunbattle with troops, residents of a nearby village to which people fled the clashes said.

There was no immediate report of casualties in the fighting in Buratai in Borno state, the home village of Tukur Yusuf Buratai, Nigeria's top army officer.