Transparency Solomon Islands has heard allegations that the new biometric registration system designed to reduce election fraud is being abused by candidates.

The group is calling on the government to make it illegal for anyone to buy or collect voter registration cards.

Transparency chief executive Daniel Fenua has received reports of one candidate buying official voter registration cards and exchanging them for his own 'supporter cards'.

He then intends to return the official cards to voters with a cash incentive to vote his way.

"Just before the polling date, their card will be given back with some cash, some influence for people to vote for them," Mr Fenua told Pacific Beat.

"Given we have this Melanesian culture of reciprocity, if someone gives you money just during that day, you feel obligated to support that person's candidacy by voting for him or her."

But Solomon Islands' chief electoral officer Polycarp Haununu argues there is no guarantee that buying votes yields results, given there is no way of knowing which candidate a voter chose.

"The rumour has it that some have bought cards but that doesn't mean that whoever's card has been held, will vote for that political candidate," Mr Haununu said.

"It's up to the electors to choose to vote for that person or otherwise."

Investigation needs formal complaint

Mr Haununu says he has not yet received any formal complaint against candidates buying voter registration cards.

He says the electoral commission and police will only be able to investigate the allegations if a formal complaint is made.

"If candidates are buying votes, people have to report such cases to the police and the police will investigate," he said.

"Unless I receive any formal complaint, I can't take the case to the police to investigate."

Mr Fenua has voiced concerns to the electoral commission over electoral fraud allegations but cannot register a formal complaint until the rumours are confirmed and more claimants come forward.

"A lot of people are too afraid to come forward and report these allegations," he said.

"They are not really brave enough to come forward and they're in fear that something will happen to them."

So far, only one "client" has come forward with a complaint to Transparency Solomon Islands.

"We are trying to get in touch with the client, [to find out] if it is OK with him for us to take that matter forward," Mr Fenua said.

"I encourage others to come in and support those kinds of similar cases."