By Brenda Goh and Hyunjoo Jin

SEOUL, June 7 (Reuters) – South Korean President Lee Jae Myung called on Sunday for a thorough investigation ‌into a ballot shortage that disrupted recent local elections, saying prosecutors ‌and police would be involved.

“As one citizen and as the president responsible for the government, I ​express deep regret,” Lee said in an X post.

Last week’s local elections were hit by a ballot shortage that prevented some eligible voters from casting ballots. The head of the National Election Commission (NEC), the independent body that oversaw the ‌vote, resigned after the incident.

Thousands ⁠have since protested outside a ballot-counting site in Seoul, demanding a re-run.

OPPOSITION CALLS FOR JOINT AUDIT

Lee said the incident was “difficult ⁠to comprehend” and that the NEC’s response and explanations were insufficient. He said he had asked parliament to conduct a fact-finding probe, establish measures to prevent ​a repeat ​and discuss reform plans for the commission.

Jang ​Dong-hyeok, leader of the opposition ‌conservative People Power Party, told a press conference on Sunday that he had visited the protests and called for a joint audit with Lee’s Democratic Party.

He said ballot shortages were especially severe in areas that lean conservative, but stopped short of calling for a re-run, saying he would “obey whatever the people’s ‌commands say”.

The Democratic Party swept major local ​races, but the opposition retained Seoul’s mayoralty, with ​incumbent Oh Se-hoon winning another ​term.

The NEC said 50 of 14,300 polling stations ran out ‌of ballots, while voting was temporarily ​suspended at 22 ​due to delays in supplies. In Seoul, delays were reported at 12 locations in Songpa district, a conservative stronghold.

At one Songpa polling station, an ​angry crowd blocked officials ‌from moving ballot boxes to be counted after voting ended.

(Reporting by ​Brenda Goh and Hyunjoo Jin. Additional reporting by Joyce Lee. Editing ​by Kim Coghill and Mark Potter)