Goodluck Jonathan says he believes international assistance will help resolve crisis as details emerge of new Boko Haram atrocity

Nigeria's president has insisted that the internationally decried kidnapping of 286 girls by Boko Haram will mark the "beginning of the end of terror" in the country, as further details emerged of the latest rebel atrocity, which saw scores of people shot and burned alive in a north-eastern market town on Monday.

The president, Goodluck Jonathan – whose efforts to contain Boko Haram's bloody five-year uprising have frequently been criticised – told delegates in Abuja for a meeting of the World Economic Forum that he believed assistance from the US and UK governments would help "resolve this crisis".

Boko Haram is holding 276 girls from a raid on a school in Chibok on 15 April and a further eight, aged between eight and 15, who were snatched from a village on Monday, also in its stronghold in north-eastern Borno state. Abubakar Shekau, the leader of the group's main faction, has threatened to sell the schoolgirls as slaves.

Addressing dignitaries including the Chinese premier, Li Keqiang, and the Kenyan president, Uhuru Kenyatta, Jonathan said: "Thank you for accepting to come even at a time we're facing attacks by terrorists. Your presence helps us in the war against terror. By God's grace, we'll defeat the terrorists. I believe the kidnap of these girls will be the beginning of the end of terrorism in Nigeria."

Jonathan's comments on Thursday echoed those earlier in the week of the US president, Barack Obama, who said the Chibok kidnappings "may be the event that helps to mobilise the entire international community to finally do something against this horrendous organisation that has perpetrated such a terrible crime".

On Wednesday, the British government announced that it would send a small group of experts to Nigeria to assist with the hunt for the missing girls. The team is expected work alongside US military and law enforcement officers who are providing technical help to the Nigerian authorities. France has offered a specialist team, while China said it would make available "any useful information acquired by its satellites and intelligence services".

Around 6,000 troops have been drafted in to protect the meeting, which had been intended to highlight Nigeria's financial progress and its recent emergence as Africa's top economy. The budget for the two-day event is twice that of the Federal Initiative for the North East – the plan aimed at boosting security in the region.

Nigeria has typically resisted security cooperation with the west, which analysts say has hampered efforts against the militants, who have killed thousands since 2009.

American officials have acknowledged that the US military has relatively weak ties with Nigeria and unlike many other African states, the government in Abuja has shown little interest in major training programmes.

"In the past, the Nigerians have been reluctant to accept US assistance, particularly in areas having to do with security," said John Campbell, a former US ambassador to Nigeria.

"Whatever assistance we might provide and might be welcomed by the Nigerian side is likely to be essentially technical," he said.

Johnson's speech came three days after Islamist rebels carried out another massacre near the north-eastern border with Cameroon.

After storming Gamboru Ngala in armoured vehicles after midday on Monday, the gunmen burned traders alive in their stalls and murdered entire families.

"We have been collecting bodies from all over the town, on the streets and in burnt homes," said a local resident, Musa Abba. "Nine members of a family were burned alive in their home."

The area senator Ahmed Zanna, who put the death toll at 300, said the town had been left unguarded because soldiers based there had been redeployed north towards Lake Chad in an effort to rescue the schoolgirls. Other estimates put the number of dead at between 100 and 150.

Nigeria's military has been repeatedly accused of leaving unarmed civilians to fend for themselves during the uprising, which Boko Haram says is aimed at creating an Islamic state in mainly Muslim northern Nigeria.

"Some bodies are burnt beyond recognition," said Babagana Goni, another resident. "Some of the bodies were shot while others had their throats slit, which made me sick. I couldn't continue the count."