The Solomon Islands Electoral Commission is concerned that some candidates may be paying citizens for their identification cards used for voting.
The CEO of the commission, Polycarp Haununu, told the Solomon Star that all citizens must keep their cards and not buckle to people offering them money.
The Star reported some candidates in Malaita are buying the cards for $7 US dollars.
It reported one candidate had acquired around 200 cards since the opening of voter registration last week.
Solomon Islands is using a new biometric voter registration system for the election later in the year.
Mr Haununu has reminded all eligible voters to register only once, and attempting to register twice is a serious offence.
The Joint Civil Society Groups & Concerned Citizens organisation has raised its concerns with the electoral office.
Voter registration is open for 40 days.