Five aid workers abducted last month in north-east Nigeria’s Borno State have been killed, reportedly by jihadists.
The men were working for Action Against Hunger, the International Rescue Committee, Rich International and the country’s State Emergency Management Agency, Nigeria’s president confirmed.
Muhammadu Buhari blamed Boko Haram and vowed to bring the killers to justice.
He also pledged to “wipe out the remaining vestiges” of the Islamist group, which has dominated the region.
The group’s decade-long insurgency has left thousands dead, displaced many more and resulted in a humanitarian crisis in north-eastern Nigeria.
Aid workers have frequently been targeted, especially by a Boko Haram splinter group affiliated to the so-called Islamic State group.
In a video released last month the hostages did not name either Islamic State or Boko Haram but referred to their captors as soldiers of the “khalifa”.
Previously, captives have used the term to refer to Islamic State West Africa Province (Iswap), rather than Boko Haram
The Nigerian online newspaper Premium Times says the killers belong to a sect of Boko Haram and posted a 35-second video of the executions.
According to the newspaper, five hooded armed men stand with the blindfolded hostages.
An unidentified voice delivers a speech to “the infidels” telling them to “repeat and turn to God” before one of the gunmen orders the others to shoot their captives.