Islamic State's West Africa branch on Thursday claimed responsibility for kidnapping six aid workers in northeast Nigeria.
International aid agency Action Against Hunger said that a staff member and five others kidnapped in Nigeria last week had appeared in a video released on Wednesday evening and that they were "apparently in a good condition of health."
Islamic State in West Africa (ISWA), which split from Nigerian Islamist group Boko Haram in 2016, claimed responsibility for the kidnap in a tweet published by the SITE monitoring group.
The group has carried out a number of attacks in the northeast over the last few months, including on military bases.
It killed a kidnapped aid worker nine months ago.
Action Against Hunger said in a statement that the people were abducted last week near the town of Damasak in northeast Nigeria, where the insurgents were active.
"Action Against Hunger strongly requests that our staff member and her companions are released," said the agency.
The video was published by The Cable, a Nigerian news organisation, and showed a woman sitting on the floor who identifies herself as "Grace". Five men sit around her, some with their heads bowed.
Behind them is a sheet with the logo of the United Nations refugee agency UNHCR.
"We were caught by this army called the Calipha," she said, before asking that the Nigerian government and Action Against Hunger secure their release. "We don't know where we are."
Separately, the Nigerian presidency said in a statement that the government was negotiating for the release of the kidnapped aid workers.
A source told Reuters that a driver was killed during the kidnap and that all six abductees were Nigerians.
