The US has imposed visa restrictions on a number of people in Nigeria accused of undermining democratic principles ahead of elections in Edo and Ondo states.
The state department said the individuals – who have not been named – had operated with impunity at the expense of the Nigerian people.
It urged all parties – including the security forces – to ensure free and fair elections.
The US also announced visa restrictions on individuals involved in elections in two other states that were marred by violence last year.
In August the US had expressed concern over the deteriorating political climate in Edo State. It said it was disappointed with the role played by some political actors in the state, especially with regards to allegations of interference by security forces in political matters.