The Eastern European, who was abducted along with a Briton in Nigeria's oil-rich Niger Delta overnight, may be a Romanian and not Bulgarian, BBC reported.
Police spokesman told the BBC News website that the second man was Romanian and that both men were snatched from an oil platform in a village called Efiat in Akwa Ibom State.
Both workers were kidnapped by unknown gunmen in speedboats near Calabar, thought to be a relatively peaceful city in the troubled region.
This latest attack comes hours after a three-year-old British girl kidnapped last week was released unharmed.
"We are in touch with local authorities and working towards an early release," David McLaughlin, a spokesman for UK High Commission in Abuja told the BBC News website.