Boko Haram Islamists have abducted 22 girls and women in two separate raids in north-east Nigeria, residents and vigilantes said.

In the first attack on Thursday, the jihadists raided the village of Pulka near the border with Cameroon where they kidnapped 18 girls.

“Boko Haram fighters from Mamman Nur camp arrived in pickup vans around 6am and seized 14 young girls aged 17 and below while residents fled into the bush,” a Pulka community leader said.

“They picked four other girls who were fleeing the raid they came across in the bush outside the village,” said the community leader who asked not to be named for fear of reprisals.

According to the official, the attackers were loyal to the faction headed by Abu Musab Al-Barnawi, the son of Boko Haram founder Mohammed Yusuf. Barnawi was appointed last year by Isis to replace leader Abubakar Shekau, who had pledged allegiance to the jihadist group in 2015.

Another resident confirmed the raid and said the girls were likely to end up as brides for the fighters. “They didn’t harm anyone during the raid and they made no attempt to shoot people running away from the village,” said the resident.

In the second incident outside the village of Dumba, close to Lake Chad, the jihadists killed a herdsman who had tried to escape after refusing to pay protection money, said Adamu Ahmed, a member of an anti-Boko Haram militia.

“When the Boko Haram gunmen came for the money they realised he had left with everything and they decided to go after him on their motorcycles,” Ahmed said. “They caught up with him near Dumba where they slaughtered him and shot dead 50 of his cattle.

“They took four women from the man’s family and the rest of the herd,” he said.

The promotion of Barnawi revealed divisions in the group, as Shekau had been criticised for mass killings and suicide attacks against civilians.

Barnawi and his right-hand man Mamman Nur, who is seen as the real leader, had promised residents in areas under their control would not be harmed as long as they did not cooperate with Nigerian troops fighting Boko Haram. But in recent weeks the Islamist fighters have intensified raids in areas near Lake Chad, stealing food from residents.

They have also killed several civilians they accused of cooperating with the military.