South Korea's ruling and main opposition parties were expected to each win at least five of the

17 metropolitan mayoral and gubernatorial posts contested in Wednesday's local elections, according to joint exit polls by local TV stations.

The ruling Saenuri Party was forecast to prevail in mayoral races in Daegu and Ulsan, and gubernatorial races in Jeju Island and its traditional power bases in South Gyeongsang and North Gyeongsang provinces, the exit polls revealed.

They also showed that the main opposition New Politics Alliance for Democracy was also expected to secure victories in mayoral races in Seoul, Sejong and Gwangju, as well as gubernatorial races in its traditional strongholds -- South Jeolla and North Jeolla provinces.

The rival parties were locked in too-close-to-call races in the country's second-largest city of Busan and Incheon, a port city of west of Seoul, as well as five other areas, according to the exit polls released right after voting was closed at 6 p.m.

Park Won-soon of NPAD was expected to be re-elected as mayor of Seoul by defeating Chung Mong-joon, a seven-term lawmaker of the ruling party who once served as FIFA vice chairman, in the biggest battleground of the local elections.

The Seoul mayorship carries an extra weight in South Korean politics as it is often deemed a steppingstone to the presidency.

Former Seoul Mayor Lee Myung-bak was elected president in 2008, running on his accomplishments as the top administrator of the capital.

The predictions were based on the combination of the results from exit polls by the nation's three major television networks -- KBS, MBC and SBS. Official electoral results are due early Thursday morning.

A total of 3,952 officials, including 17 metropolitan mayors and provincial governors, and 226 heads of low-level administrative units will be chosen in the first nationwide elections in two years, according to the National Election Commission.

The polls, widely seen as a referendum on President Park Geun-hye's performance, come as South Korea is still reeling from April's ferry disaster that has claimed nearly 300 lives and has battered public confidence in the government due to its botched handling of the tragedy.

The election campaign has been dominated by pledges to improve public safety, which has emerged as the top priority for many voters following the ferry disaster and a series of recent deadly accidents. (Yonhap)