South Korea's ruling liberal party won a majority of races in Wednesday's local elections but lost the crucial Seoul mayoral contest in a setback to efforts to give President Lee Jae Myung a firmer political mandate.

South Koreans are voting in mayoral and other local elections that are seen as a gauge of support for President Lee Jae Myung’s 1-year-old liberal government.

Exit polls show South Korea’s ruling liberal party has been projected to win a landslide victory in mayoral and other local elections

The liberal Democratic Party (DP) looks set to win a resounding victory in Wednesday's local elections, according to a joint exit poll announced shortly after voting ended.