Voters wait in front of a polling station in Seoul's Songpa District, at 9:45 p.m. Wednesday, as voting was extended to 10 p.m. from 6 p.m. due to a shortage of ballots. Yonhap

The main opposition People Power Party (PPP) leader Jang Dong-hyeok called for an immediate halt to vote counting, Wednesday, until the cause of ballot shortages at several Seoul polling stations during the day's local elections could be determined.

“The Seoul election has been tainted. A tainted election is invalid," Jang said. "Once counting proceeds and wraps up, there will be no way to properly investigate what happened. Counting must stop right now.”

Jang added that depending on the findings, the suspension should extend to all affected areas, including Seoul and Incheon, and that a by-election should be held if irregularities are confirmed.

NEC Secretary General Heo Cheol-hoon apologized for the disruption during a briefing Wednesday evening.