Nauru opposition MP Mathew Batsiua said local media was refusing to broadcast his campaign advertising without permission from the authorities.
The general election is tomorrow and about eight thousand eligible voters must cast their ballots or pay a $US15 dollar fine.
Mr Batsiua said there wasn't a level playing field for election candidates in Nauru media.
"They said they'd have to review it first and have it approved by the authorities before they can show it. That shows just how difficult it is for us to get a fair chance of advertising using public broadcasts here in Nauru."
The Nauru government has rejected Mr Batsuia's claim saying local media in Nauru has a long standing policy of not airing political advertising from either side.
Listen to Ben Robinson-Drawbridge's report