The by-election for the chief of Seoul's key district ended with a turnout of 48.7 percent on Wednesday, the election watchdog said, with the result expected to serve as a key barometer of voter sentiment ahead of the parliamentary elections slated for April next year.

More than 243,665 of Gangseo Ward's 500,603 eligible voters cast their ballots at polling stations from 6 a.m. to 8 p.m., according to the National Election Commission.

The potential winner is expected to emerge late Wednesday.

Although the election will only decide who will become one of Seoul's 25 ward chiefs, it has gained much attention, with the turnout for the two-day advance voting recording the highest ever in the country's by-election history.

During the early voting on Friday and Saturday, 113,313 out of the 500,603 eligible voters cast their ballots, representing a turnout of 22.64 percent, the NEC said.

The by-election takes place after former ward chief Kim Tae-woo was removed from the post in May due to a suspended prison sentence for leaking secrets he gained while working for a special inspection team under former President Moon Jae-in.

Although the seat was vacated due to Kim's conviction, the ruling People Power Party (PPP) has named him as its candidate after his right to run in the election was reinstated following a special presidential pardon in August.

Kim's rival in the main opposition Democratic Party is Jin Kyo-hoon, a former deputy chief of the national police.

A total of six candidates are running in the by-election, including Kim and Jin.

Rival parties have each made a final plea for voters' support for their respective candidates, with the PPP saying Kim is the right person who will be working for the Gangseo constituency.

The DP, meanwhile, has appealed for support for Jin, arguing that winning the seat will serve as an opportunity to showcase judgment of the Yoon Suk Yeol administration. (Yonhap)