Five officials of a minor progressive party have been arrested on court-issued warrants in connection with fraud by the party ahead of the most recent parliamentary elections in April, prosecutors said Thursday.

The five officials of the United Progressive Party (UPP) are suspected of taking a leading role in manipulating the party's internal race to nominate candidates for proportional representation seats, including enabling multiple voting by some members friendly to the then party leadership, the prosecutors said.

Prosecutors earlier sought arrest warrants for a total of 14 former and current party officials, but the court rejected the requests for the nine others.

The voting fraud dealt a heavy blow to the party after it failed to oust two lawmakers -- Lee Seok-ki and Kim Jae-yeon -- who won seats on proportional representation tickets as a result of the rigged voting.

The UPP is the third-largest party, with six seats in South Korea's 300-member parliament. (Yonhap News)