South Korea's ruling conservative party has won control of parliament in a nationwide election seen as a preview of presidential elections later this year.

Wednesday's election results give a boost to President Lee Myung-bak's ruling New Frontier party, which will hold onto its majority in parliament.

The voting was to fill 300 seats in the National Assembly, with 246 of the legislators to be elected directly. The remainder are chosen through proportional representation.

This is the first time in 20 years that the parliamentary and presidential elections are taking place in the same year. The results likely will have an impact on the December presidential vote. President Lee cannot run for re-election.

The opposition has accused the New Frontier party of supporting the rich and privileged at the expense of ordinary South Koreans.

Elections for South Korea's unicameral parliament are held every four years. The country has about 40 million eligible voters.