UPDATE 2-Islamic State claims aid workers' kidnap in northeast Nigeria

(Adds ISWA claim, presidency comment, change dateline to Abuja)
ABUJA, July 25 (Reuters) - 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.