A new episode in the row between the West African neighbors who have trading accusations of hostility since May.
This week Benin arrested five Nigerien nationals on accusations of entering the port of Seme illegally.
Niger responded by accusing Benin of kidnapping staff of its oil company who it said were at the port to witness the loading of an oil shipment.
Benin claims two of the detainees are agents of Niger's army junta, and that they used fake documents to access the facility.
The port of Seme has become a flashpoint in relations between the neighbours.
Landlocked Niger runs a pipeline from its oilfields to the port where its crude on loaded into tankers for export.
But in May, Benin blocked the shipment of oil accusing Niamey of refusing to reopen its border to trade. The blockade on oil shipments was later lifted following China's intervention.
Niger shut its borders following an army takeover last July. Benin has since reopened its side of the border and has requested Niger to do the same.
But Niger accuses Benin of hosting French troops on its soil which it says seek to destabilize it.
