South Korea's main opposition party has seized control of the country's National Assembly after dramatic by-election wins.

Voters handed defeats in key constituencies to allies of President Kim Dae-jung, who is entering his final months in office.

Lee Hoi-chang's party now has power ahead of his presidential bid

Candidates from the main opposition Grand National Party won 11 of the 13 districts being contested, including all three high-profile seats fought in Seoul, the National Election Management Committee said.

Those wins give a majority in the single-chamber parliament to the conservative GNP, which is critical of President Kim's "sunshine" engagement policy with North Korea.

Mr Kim's Millennium Democratic Party, plagued by a series of corruption scandals involving government officials and two of his three sons, won two seats on the president's political home turf in the south-west of the country.

Presidential predictions

The by-elections were widely seen as giving a verdict on Mr Kim's rule and as a guide to December's presidential elections.

GNP leader Lee Hoi-chang, who narrowly lost a 1997 election to President Kim, is running for president again this year.

Opinion polls show him leading the pro-government candidate Roh Moo-hyun ahead of the 19 December vote.

Mr Kim is barred from running again by the constitution.

Mr Lee's party wins secured more than the nine seats it needed to hold a majority in the legislature until the next general election in April 2004.

Apathy and unease

The independent election commission said the turnout was just 29.7% - a new national low.

Mr Kim's choice of prime minister was vetoed

Correspondents said many voters were on holiday, put off by the country's scandal-ridden politics or busy cleaning up after torrential rains which flooded thousands of homes and killed at least five people.

Analysts said a poor showing by the ruling Millennium Democratic Party (MDP) could hasten its disintegration.

The previous popularity of the president and goodwill generated during South Korea's joint hosting of the football World Cup has been severely tested recently with political rows hotting up ahead of the December race.

President Kim's nomination of a woman as South Korea's first prime minister was blocked by the opposition.

And from the other side, draft-dodging allegations against Mr Lee's son have been wheeled out again, five years after they contributed to his defeat in the 1997 presidential poll.