Nigeria's president has described as a "heinous atrocity" the latest wave of attacks by Boko Haram militants that left more than 150 people dead.
Muhammadu Buhari also called for a faster deployment of a regional military force to fight the Islamists.
The gunmen have been launching attacks on remote villages in the north-eastern Borno state since Tuesday, targeting people attending evening prayers.
Mr Buhari - who was sworn in in May - sees fighting Boko Haram as a priority.
According to Amnesty International, at least 17,000 people, mostly civilians, have been killed since 2009, when Boko Haram launched its violent uprising to try to impose militant Islamist rule.
Will new military HQ make a difference?
Why Boko Haram remains a threat
'They spared nobody'
These are the worst Boko Haram attacks for many weeks, BBC Nigeria correspondent Will Ross reports.
In a statement on Friday, President Buhari said the recent attacks were "inhuman and barbaric."
He said they were "the last desperate acts of fleeing agents of terrorism".
The assaults began on Tuesday, when the militants shot dead 48 men after they had finished prayers in two villages near the town of Monguno, a resident told BBC Hausa.
He said he had heard gun shots at one of the villages attacked and saw it on fire.
"They were praying in the mosque when Boko Haram attackers descended on the village. They waited till they finished the prayers. They gathered them in one place, separated men from women and opened fire on them," he said.
On Wednesday, more than 50 gunmen killed 97 people in the village of Kukawa, near Lake Chad, eyewitness Babami Alhaji Kolo was quoted as saying by the AFP news agency.
"The terrorists first descended on Muslim worshippers in various mosques who were observing the Maghrib prayer shortly after breaking their fast [for the Muslim month of Ramadan]," he said.
"They... opened fire on the worshippers who were mostly men and young children. They spared nobody."
On Thursday, two female suicide bombers blew themselves up in another Borno village, police said.
Muhammadu Buhari also called for a faster deployment of a regional military force to fight the Islamists.
The gunmen have been launching attacks on remote villages in the north-eastern Borno state since Tuesday, targeting people attending evening prayers.
Mr Buhari - who was sworn in in May - sees fighting Boko Haram as a priority.
According to Amnesty International, at least 17,000 people, mostly civilians, have been killed since 2009, when Boko Haram launched its violent uprising to try to impose militant Islamist rule.
Will new military HQ make a difference?
Why Boko Haram remains a threat
'They spared nobody'
These are the worst Boko Haram attacks for many weeks, BBC Nigeria correspondent Will Ross reports.
In a statement on Friday, President Buhari said the recent attacks were "inhuman and barbaric."
He said they were "the last desperate acts of fleeing agents of terrorism".
The assaults began on Tuesday, when the militants shot dead 48 men after they had finished prayers in two villages near the town of Monguno, a resident told BBC Hausa.
He said he had heard gun shots at one of the villages attacked and saw it on fire.
"They were praying in the mosque when Boko Haram attackers descended on the village. They waited till they finished the prayers. They gathered them in one place, separated men from women and opened fire on them," he said.
On Wednesday, more than 50 gunmen killed 97 people in the village of Kukawa, near Lake Chad, eyewitness Babami Alhaji Kolo was quoted as saying by the AFP news agency.
"The terrorists first descended on Muslim worshippers in various mosques who were observing the Maghrib prayer shortly after breaking their fast [for the Muslim month of Ramadan]," he said.
"They... opened fire on the worshippers who were mostly men and young children. They spared nobody."
On Thursday, two female suicide bombers blew themselves up in another Borno village, police said.
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