The protests are against plans to increase temporary working

Hyundai said the strike by unionised workers would cost the firm 80 billion won($75.67m; �40.11m).

An official at Hyundai's sister firm, Kia Motors, said the walkout would result in the loss of 3,447 vehicles and $45m (�24m).

The last spate of strikes in the country's car sector occurred in July when a wage dispute sparked a walkout.

That strike is reckoned to have added 14% to Hyundai's labour costs this year.

On Friday, the Korean Confederation of Trade Unions (KCTU) said a total of 157,999 workers at 398 workplaces had responded to the latest national strike call.

However, the labour ministry claimed about half that number had taken part in the stoppage, held in protest at a bill aimed at allowing companies to hire more temporary workers and ban strikes by civil servants.

The KCTU, which has 620,000 members, is also demanding the government halt free trade talks with Japan.

Further strike threat

Hyundai's union initially wanted to stay out until Monday, but limited its action to one day on advice from the KCTU.

Poor labour relations keep Hyundai from growing

"KCTU leaders met with ruling and opposition party officials and got an answer that lawmakers would not force through parliamentary approval," said Chang Gyu-ho, a Hyundai union spokesman.

"They promised they would seek a solution through dialogue, but in case they try to pass the revised laws we would respond with even stronger strike action."

The July walk-outs cost the firm over $228m and prompted thousands of workers across the motor sector to follow suit.

Poor labour relations are thought to be a key factor in keeping Hyundai from becoming one of the world's top five auto makers.

Union members say the labour bill, awaiting parliamentary approval, will weaken job security and worsen working conditions, as it will allow firms to employ temporary workers freely for up to three years from 2006.