The Romanian works for a construction firm and was abducted in Delta state on Monday
Officers have launched a search for the man in the area of Owa Oyibo, where he was abducted late on Monday, said Celestina Kalu, a spokeswoman for police in Delta state.
He was working for Dextron Nigeria Ltd, a construction firm, Kalu added.
The southern swampland has been hit by a wave of militant attacks on oil and gas facilities and a general breakdown of law. Militants are fighting for a greater share of oil revenues for the impoverished Niger Delta, which is home to much of Nigeria's oil production.