African leaders meeting in Paris have agreed to wage "war" on Nigeria's Boko Haram Islamic militants.
President Hollande of France, who hosted the summit, said regional powers had pledged to share intelligence and co-ordinate action against the group.
Last month it abducted 223 schoolgirls in north-eastern Nigeria, where it is based. Fresh attacks were reported in Nigeria and Cameroon overnight.
Thousands of people have been killed by Boko Haram in recent years.
The Paris summit brought together President Francois Hollande, Nigeria's Goodluck Jonathan, and their counterparts from Benin, Cameroon, Niger and Chad.
Afterwards, Mr Hollande said participants had agreed on a "global and regional action plan".
He said this involved "co-ordinating intelligence, sharing information... border surveillance, a military presence notably around Lake Chad and the capacity to intervene in case of danger".
Cameroon's President Paul Biya said: "We are here to declare war on Boko Haram". Idriss Deby of Chad said it would be "total war".
Earlier, Mr Hollande called Boko Haram a "major threat to West and Central Africa", and said it had links with al-Qaeda's North-African arm and "other terrorist organisations".
BBC's International Development Correspondent Mark Doyle says the group is an international threat, drawing fighters from not just Nigeria but also from neighbouring Niger, Cameroon and Chad.
In the latest violence, suspected Boko Haram militants attacked a camp run by a Chinese engineering company in the far north of Cameroon, near Nigeria's north-eastern border.
Ten Chinese workers are believed to have been abducted. One Cameroonian soldier was killed, officials say.
In Nigeria itself, 11 people were reported killed in a separate attack on a village a few hours' drive from the Cameroonian border.
A relative of one of the victims said a woman and a child were among the dead.
Representatives from the UK, US and EU also took part in the Paris meeting.
Before it began, UK Foreign Secretary William Hague said regional powers needed to co-operate better when it came to cross-border intelligence.
Boko Haram has some of its bases in the Mandara mountain range that straddles the border. But the long frontier has been disputed in at least two places in recent years.
The abducted schoolgirls, who include Christians and Muslims, were seized on 14 April in the north-east Nigerian town of Chibok in Borno state.
Mr Jonathan was due on Friday to visit the town but the trip was cancelled for security reasons.
Boko Haram released a video earlier this week showing more than 100 of the girls and offering an exchange for prisoners.
President Jonathan has ruled out negotiations over their possible release, officials say.