Former Seoul Mayor Oh Se-hoon has been selected as the main opposition People Power Party's(PPP) candidate to run in the April Seoul mayoral by-election.

The PPP on Thursday announced the results of party primaries for mayoral posts in Seoul and Busan.

Oh was declared the winner of the primary against former four-term lawmaker Na Kyung-won. Oh won 41-point-64 percent of votes in a survey held on Tuesday and Wednesday, while Na secured 36-point-31 percent. 

Oh will now compete against former Startups Minister Park Young-sun of the ruling Democratic Party in the Seoul mayoral race. 

As for the Busan mayoral by-election, DongA University professor Park Heong-joon was elected as the party's candidate with 54-point-four percent of votes in the primary.