South Korean authorities are reportedly investigating the country's National Election Commission after polling stations ran out of ballots on June 3 during nationwide regional elections. 

The ballot shortage resulted in the resignation of NEC chief Roh Tae-ak and demonstrations demanding an election re-run, according to Agency France Press.

President Lee Jae Myung has ordered a "thorough" investigation, the news outlet also reports. And a joint team of police and prosecutors said Thursday it was raiding the NEC's offices over indications that officials falsified voter turnout figures.

"We have found indications that officials from the National Election Commission and the Gyeonggi Provincial Election Commission entered false voter turnout figures during the local elections," the team's spokesman told reporters.

Investigators are probing whether some officials manipulated the election statistics system to correct earlier errors in voter turnout figures on the day of the local elections.

Any correction to reported turnout figures must go through a formal approval process, according to NEC rules.

Instead, investigators suspect some officials adjusted figures in multiple polling stations to keep the totals consistent while waiting for actual turnout numbers to catch up, bypassing the required reporting process.

The ballot paper shortage affected at least 90 polling stations with people unable to cast their June 3 ballots, Reuters reported.