Protesters chant slogans outside the Olympic Park Handball Gymnasium in southern Seoul, Thursday, in protest of ballot shortages during the June 3 local elections. Yonhap

Police are investigating an alleged break-in at a ballot-counting center amid weekslong protests calling for a rerun of the June 3 local elections, sports officials said Friday.

According to the Korea Sports Industry Development (KSID), which manages the Olympic Park Handball Gymnasium that was used as a vote-counting center for the elections, three unidentified individuals broke into the facility on June 7 after damaging a basement door lock.

The KSID reported the case to the police, along with surveillance camera footage showing the individuals entering the gym and filming the interior.

After filing the complaint, the KSID welded the basement door shut on June 11. Video of the welding spread online, sparking unverified conspiracy theories that authorities intended to trap protesters inside the gym and start a fire or crowd crush.