The head of South Korea's left- leaning opposition party said Tuesday the fledgling party will soon be disbanded and a new splinter party will be created next month.

The United Progressive Party was dealt a lethal blow last month after failing to oust two lawmakers involved in a rigged party primary, which had helped them win parliamentary seats in April as proportional representatives.

The scandal spawned bitter infighting between supporters and foes of the two newbie legislators, Lee Seok-ki and Kim Jae-yeon, and threatened to delegitimize the party whose new-found status as the third largest party in the 300-member parliament was once considered a major success.

The controversy had then escalated into a national debate on the two lawmakers' leftist political views, with conservative critics calling both Lee and Kim sympathizers of the Democratic People's Republic of Korea (DPRK), South Korea's wartime enemy.

"The party is (in disarray) because of the dominance of a political faction, and we need to part with that faction," party chairman Kang Ki-gab said in an interview with YTN radio earlier in the day, referring to a mainstream faction within the party that sided with the two disgraced lawmakers.

The faction, which has resisted reform efforts led by Kang and others, is also known for its pro-Pyongyang views.

"Whatever happens, we will complete the creation of a new progressive party in September," Kang, one of the leading reformists within the party, said without elaborating.

The leftist party was founded last year through a merger among three progressive parties, an ambitious shot at changing South Korea's political landscape dominated by centrists and conservatives.