Fraud and irregularities prevailed in the United Progressive Party’s process to select its proportional representative candidates, the far-left minority party said Wednesday.

“Problems found (in the primary) are grave enough to judge that the whole process and its results have lost legitimacy and credibility,” Cho Jun-ho, one of the four co-chairs of the party, told a press conference at the National Assembly in Seoul.

Announcing the results of a three-week internal investigation, he concluded that his party was not prepared to handle such a vote by party members, yet it pushed ahead.

The result was a total failure of election management, which led to fraud and errors, he added.

The findings plunged the UPP into its biggest crisis ever, as it gears up to join the incoming parliament as the third-largest bloc.

Party leaders cancelled a gathering of its 13 lawmakers-elect, including six proportional representatives, scheduled for the day, and spent hours discussing the situation.

A prosecutorial probe looks likely, local media reports said, citing unidentified prosecutorial officials.

Korea’s political parties have often been found guilty of corruption and election irregularities. A former chief of the ruling Saenuri Party was recently found to have bribed party delegates and members to win the party’s leadership election.

Yet, the latest case could shake the UPP to its core, as the far-left group is built on a self-image of higher standards and has harshly criticized larger parties for being corrupt and undemocratic, political observers said.

They said the fraud in the party’s candidate nomination process may have been the result of a power struggle amongst three factions within the UPP over the control of the party.

The UPP was created last December by the merger of three groups: the Democratic Labor Party led by Lee Jung-hee, People’s Participation Party led by Rhyu Si-min and a group of defectors from the New Progressive Party led by Sim Sang-jeong.

Lee, Rhyu and Sim now co-chair the UPP, along with Cho.

Heading into the April general election, the UPP held a vote of party members to decide its list of proportional representative candidates. Members cast their ballots in three ways: in person at polling stations, via the party’s website or through their cellphone.

Irregularities were found in on-the-scene and online balloting, Cho’s team found. In many ballot boxes, the number of votes cast did not match the number of people that showed up to vote, suggesting ballot stuffing.

The firm in charge of operating online voting also corrected its program while the balloting was under way, making it possible the firm manipulated the results.

By Lee Sun-young (milaya@heraldcorp.com)