Gunmen stormed the premises of a Lebanese construction company Setraco on Saturday night, killing a security guard and abducted an Italian, a Greek, a Briton and four Lebanese nationals.
The attack happened in Jama're, a town in northern Bauchi state.
The group sent an e-mail to journalists claiming that it has in its custody seven persons which include Lebanese and "their European counterparts working with Setraco”.
The group has earlier been linked to al Qaeda by the British government.
Ansaru whose full name is Jama'atu Ansarul Musilimina Fi Biladis Sudan said its reason for the abduction was due to "the transgression and atrocities" committed on Muslims by the European countries in many places such as Afghanistan and Mali.
It criticised the French support for the war against insurgents in Mali and saw it as a justification for an earlier kidnapping in December.
Many attacks, including suicide bombings, killings and explosions in Nigeria's northern states have been claimed by Islamic extremist group Boko Haram.
Last week, assailants had killed three medical doctors in the town of Potiskum in the northern state of Yobe.
However, the new insurgent group Ansaru has carried out most of the kidnappings of foreign workers.
A combined rescue operation by Nigerian and British forces for a Briton and Italian the group abducted last year had failed.
Abuja: A new Islamic extremist group Ansaru on Monday claimed responsibility for the kidnapping of seven foreign workers, mostly Europeans, in northern Nigeria.
First Published: Monday, February 18, 2013, 20:45