At least 59 children have been killed in Nigeria after Islamist gunmen opened fire at a boarding school before burning it to the ground, officials say.

Members of the Boko Haram group targeted secondary school students as they slept in a dormitory, police say.

Military spokesman Lazarus Eli said the gunmen "opened fire on student hostels" at the Federal Government College, which is in the town of Buni Yadi in Yobe state and attended by students aged 11 to 18.

"Some of the students' bodies were burned to ashes," police commissioner Sanusi Rufai said.

Bala Ajiya, an official at the Specialist Hospital Damaturu, said: "Fresh bodies have been brought in. More bodies were discovered in the bush after the students who had escaped with bullet wounds died from their injuries."

The name Boko Haram means "Western education is sinful" and school attacks have featured prominently in the group's four-and-a-half-year Islamist uprising, which has killed thousands of people.

The police chief said all the victims in Monday's attack were boys, and the school's 24 buildings, including staff quarters, had been completely destroyed by fire.

He and the state governor, Ibrahim Geidam, were due to travel to the site to assess the extent of the damage.

President Goodluck Jonathan called the attack a "callous and senseless murder ... by deranged terrorists and fanatics who have clearly lost all human morality and bestiality".

Attack comes days after Boko Haram threat

Captain Eli, said "our men are down there in pursuit of the killers", but gave no further details.

Yobe is one of three north-eastern states placed under emergency rule in May last year when the military launched a massive operation to crush the Boko Haram uprising.

The military action has failed, triggering reprisals against civilians, and the government's failure to protect its citizens is fuelling anger in the region.

More than 1,000 people have been killed in the north-east since the emergency measures were imposed.

At least 40 students were killed in September at an agriculture training college in Yobe after Boko Haram gunmen stormed a series of dorms in the middle of the night and sprayed gunfire on sleeping students.

This month they have killed more than 300 people, mostly civilians, including in two attacks last week that killed about 100 each, one in which militants razed a whole village and shot panicked residents as they tried to flee.

Boko Haram - declared a terrorist organisation by Nigeria and the United States - has said it is fighting to create an Islamic state in Nigeria's mainly Muslim north.

Mr Geidam and the governor of neighbouring Borno state, Kashim Shettima, have fiercely criticised the military's record in combating Boko Haram, insisting more resources were needed to defeat the emboldened and increasingly well-armed insurgents.

In a video sent to AFP last week, Boko Haram's purported leader, Abubakar Shekau, said he would continue his relentless campaign of violence on anyone who supported democracy or so-called Western values.

AFP/Reuters