Nigeria has the largest number of children in the world who are not being educated, the government has said.
Acknowledging the scale of the problem the education ministry's permanent secretary Adamu Hussaini said it was "sad to note" that Nigeria had 10.5 million children out of school.
This is the first time senior officials have admitted the size of the problem.
Cultural factors have been blamed but critics point to a lack of money going to publicly funded schools.
The UN's children's agency, Unicef, has been campaigning on this issue as well as a number of other groups.
On a visit to the country last week, education activist Malala Yousafzai met acting president Yemi Osinbajo and asked him to declare what she called "an education state of emergency in Nigeria".
Mr Hussaini said those most affected were girls, street children and the children of nomadic groups and added that economic prosperity can only be achieved with an "inclusive and functional education system".
But BBC Hausa editor Jimeh Saleh says the failure in the education system is due to a lack of government funding, rather than any cultural factors as suggested by the ministry.
"Government funded schools in Nigeria have practically collapsed over the years because of poor funding leaving children from poor homes with nowhere to go but the streets," he says.
Unicef estimates that 60% of Nigerian children not attending school live in the north of the country.
A Nigerian state governor says he expects President Muhammadu Buhari to return home from the UK within the next two weeks.
Governor Rochas Okorocha was a member of a delegation who met the president in London on Sunday.
Mr Buhari has been receiving treatment in the UK for an unspecified illness.
His absence has led to some anxiety in Nigeria, with some speculating that he might have died. Others have worried he may not be able to return to duty.
The presidency later released images of Mr Buhari, 74, at the meeting with governors from his party. It is the first time he has been pictured in London since leaving Nigeria almost 80 days ago.
The Imo state governor told the BBC's Newshour programme on Monday: "I met a very hardy man in high spirits, and he's doing quite well. He has not lost his sense of humour, for which is he known for.
"So he is doing quite well and we are very pleased to see him and I think that has gone a long way to reassure Nigerians about the health of their president."
Mr Okorocha earlier said Mr Buhari had laughed off rumours concerning his health when asked about them.
"President Buhari was completely unperturbed by the cocktail of lies. He, instead, sent his best wishes to Nigerians."
Mr Buhari would be returning as soon as doctors gave him the green light, Mr Okorocha said.
The president left Nigeria on 7 May - his second trip to the UK for treatment this year.
In his absence, he has given Vice-President Yemi Osinbajo full powers to act as head of state.
Buhari's unhealthy start to 2017
19 January: Leaves for UK on "medical vacation"
5 February: Asks parliament to extend medical leave
10 March: Returns home but does not resume work immediately
26 April: Misses second cabinet meeting and is "working from home"
28 April: Misses Friday prayers
3 May: Misses third consecutive cabinet meeting
5 May: Appears at Friday prayers in Abuja
7 May: Travels to UK for further treatment
6 June: Buhari's wife says he is “recuperating fast”
12 July: Acting head of state says the president will be home " very soon”
Suspected Boko Haram fighters have been "brutally tortured" by security forces in Cameroon, a rights group says.
Amnesty International said in a report that the suspects, including women and children, were beaten, water-boarded and forced into stress positions.
The cases allegedly happened between 2013 and 2017, and dozens of detainees died as a result, it added.
Cameroon's government has not commented. Boko Haram frequently carries out attacks in the country.
The Islamist group, based in neighbouring Nigeria, has killed more than 1,500 civilians in Cameroon since 2014, and abducted many others, Amnesty said.
Victims described a least 24 methods of torture at more than 20 different sites, the report said.
In one of those places, it said, there was the presence of US and French military personnel. There was no evidence that foreign forces were involved, but Amnesty urged both countries to investigate the allegations.
The report added that people suspected of supporting the militants were often being detained without evidence.
At least nine people were killed and 10 others seriously injured Sunday when a gas tank exploded at a fuel complex in southeastern Nigeria, state police said.
There was no immediate explanation for the blast at a facility belonging to Nigerian firm Linc Oil and Gas at Calabar, said Hafiz Inuwa, in charge of the Cross River State Police Command.
The police chief, speaking at the scene, said the facility's manager had not yet explained: "what led to the explosion".
"For now, nine people are confirmed dead and many others who sustained different burns are currently receiving treatment" in a local hospital, he added.
"The figure could be more than nine, while at least 10 persons sustained various degrees of life-threatening injuries," a worker at the facility told AFP on condition of anonymity after the early morning blast.
Fuel explosions are common in Nigeria, Africa's biggest oil producer and the continent's most populous country, where it is transported on badly-maintained roads by trucks in a poor state of repair.
Accidents occur regularly when pipelines are damaged by looters stealing crude oil.
President Muhammadu Buhari is "recuperating fast" and will return home "very soon", says Nigeria's acting head of state Yemi Osinbajo.
He made the announcement at a press conference on Wednesday morning, after visiting Mr Buhari at the London hospital where he is being treated for an unspecified illness.
Mr Osinbajo, now back in Nigeria, said he had discussed a wide range of issues during the hour-long meeting.
Mr Buhari has been in London since May.
The 74-year-old leader was elected to power in 2015, becoming the first Nigerian opposition leader to win an election.
It is his second period of medical leave in the UK, the first began in January and he returned home in March.
His long absence has led to speculation about whether he will be able to resume his presidential duties.
In his absence, President Buhari has given Vice-President Osinbajo full powers to act, in contrast to the situation in 2009, when the long illness of then President Umaru Yar'Adua led to a power vacuum.
Earlier this week, Nigeria's first lady Aisha Buhari launched a cryptic attack, apparently aimed at powerful ruling party politicians suspected of manoeuvring for the presidency or deputy presidency while her husband was ill.
In a Facebook post, Mrs Buhari warned that "hyenas and jackals" would be banished.
The vice-president has been acting in Mr Buhari's place while he is out of the country, but there is no suggestion he is part of any plot against the leader, says the BBC's Naziru Mikailu.
Mrs Buhari's comments came in response to a post from Senator Shehu Sani, who warned that people were "scheming... so that they can be kings".
"Prayers for the absent Lion King has waned," he wrote. "Now the hyenas and the jackals are scheming and talking to each other in whispers; still doubting whether the Lion King will be back or not."