An armed group that kidnapped humanitarian workers in northeastern Nigeria five months ago has claimed it killed four hostages, international aid agency Action Against Hunger said on Friday.

Six people were abducted in July near the town of Damasak, Borno state, where Islamist insurgents operate.

Islamic State in West Africa Province (ISWAP), which split from the militant group Boko Haram that began its insurgency in 2009, has become the dominant jihadist group in the region. The decade-long Islamist insurgency has caused the deaths of some 30,000 people and driven 2 million to flee their homes.

Action Against Hunger said one of its employees, two drivers and three health ministry workers were abducted. In September it said one of the hostages had been killed.

On Friday, the humanitarian agency said the group claimed to have killed four of the remaining five hostages.

“Action Against Hunger condemns these latest killings in the strongest terms and deeply regrets that its calls for the release of the hostages have not been acted upon,” it said.

It also called for the “immediate release” of its staff member, Grace, who remains in captivity.

Reuters