Militants in Nigeria have raided three villages and killed those they accused of being anti-Boko Haram vigilantes, residents have told the BBC.
More than 30 people were killed in the attacks overnight into Friday in north-eastern Borno state, they said.
The raids took place as the UN Security Council approved sanctions against the Islamist group.
It is five weeks since Boko Haram kidnapped more than 200 schoolgirls, prompting international outrage.
Nigerian officials say President Goodluck Jonathan is due to travel to South Africa for discussions with other African heads of state on combating terrorism in Africa following on from last weekend's summit hosted by France.
Earlier his Rwandan counterpart, Paul Kagame, said African presidents should take responsibility for their failures and resolve their own conflicts together.
"I find that our leaders, who should have been working together all along to address these problems that only affect their countries, wait until they are invited to go to Europe. Why does anybody wait for that? What image does it even give about Africa?" he said.
Residents from two of the villages that came under attack said militants had arrived in a convoy and gathered the men of the community together.
They accused them of being members of vigilante groups and killed them all, one villager from Moforo in Marte district who escaped across the border to Cameroon told the BBC Hausa service.
They then burnt down all the shops in the market, leaving the villagers destitute, he said.
Correspondents say that most villages have formed vigilante groups to try to protect their communities from militant attacks.
A resident of Kimbi village in Biu district said the villagers contacted the security forces to alert them to their attack, but were told it was not an area under military control so they could not be helped.
The military has not commented on the allegation.
About 25 men were killed in Moforo, another eight men in Kimbi. It is not known if there were casualties from a raid early on Friday on Kabrihu village near the Sambisa forest.
The latest attacks came after another deadly village raid in Borno and twin bombings which killed 122 in the central city of Jos on Tuesday. The authorities also suspect Boko Haram of being behind those attacks, but there has so far been no claim of responsibility from the group.
Boko Haram was added to the UN Security Council's al-Qaeda Sanctions Committee's list of designated entities on Thursday at the request of Nigeria.
US envoy Samantha Power said it was an "important step" in support of efforts to "defeat Boko Haram and hold its murderous leadership accountable".
Analysis: Will Ross in Abuja
It appears staggering that it has taken this long for the UN to take this action. Boko Haram has carried out an extremely brutal campaign of violence especially over the last five years, killing thousands. The Chibok kidnapping was the game changer along with the bombings. The UK and US took similar steps last year but since then the situation on the ground has deteriorated.
Will asset freezes, arms embargoes and travel bans make any difference? Boko Haram is largely financed through bank robberies, extortion, other al-Qaeda groups and ransom payments whilst the region is awash with arms, and barracks have often been looted.
The UN decision suits the Nigerian government which wants to portray Boko Haram as an international issue partly to deflect criticism. The insurgents cross borders but it is chiefly a domestic problem. The kind of travel ban that would suit the vulnerable people in the north-east would be one which stops convoys of militants roaming freely, dishing out terror.
Analysts say it is hard to say what practical effect the move will have.
Boko Haram, which has killed thousands of people in Nigeria through a wave of bombings and assassinations since 2009, is fighting to overthrow the government and create an Islamic state.
The government's failure to prevent attacks since launching an offensive against Boko Haram a year ago has triggered widespread anger, especially since the kidnapping of the schoolgirls from Chibok in Borno on 14 April.
Meanwhile, residents in Bauchi, which is not one of three states under emergency rule because of the insurgency, say the air force repeatedly bombed a forest where there are suspected militant camps on Thursday morning.
Nigeria under attack
- 20 May: Twin bomb attacks killed at least 118 people in the central city of Jos
- 18 May: Suicide blast on a busy street in northern city of Kano kills four, including a 12-year-old girl
- 5 May: Boko Haram militants slaughter more than 300 residents in the town of Gamboru Ngala
- 2 May: Car bomb claims at least 19 lives in the Nigerian capital, Abuja
- 14 April: Twin bomb attack claimed by Boko Haram kills more than 70 at an Abuja bus station; the same day, the group abducts more than 200 schoolgirls from the remote northern town of Chibok