Gunmen killed a security guard and abducted a Briton, an Italian, a Greek and four Lebanese workers after storming the housing compound of Lebanese construction firm Setraco in Jama'are in Bauchi state late on Saturday.
It was the worst case of foreigners being kidnapped in the mostly Muslim north of Africa's most populous country since an insurgency by Islamist militants intensified two years ago.
"By Allah's grace (we) have the custody of seven persons, which include Lebanese and their European counterparts working with Setraco," read a statement from Ansaru, a group that has kidnapped other foreigners in Nigeria in the past.
The group has risen to prominence only in recent months.
It has claimed responsibility for kidnapping a Frenchman last year and a raid on a major police station, where it said hundreds of prisoners were released. Britain said the group was behind the kidnap of a British and a Italian killed last year during a failed rescue attempt.