South Korea's motor industry was hit by nationwide strikes on Tuesday at Hyundai, Kia and Ssangyong, with unions demanding higher wages and better working conditions.

The Associated Press (AP) said the 41,000-member union at Hyundai Motor, the nation's top car manufacturer, staged a full-day strike after partial walkouts on Friday and Monday while another 23,000 laid down their tools at Hyundai affiliate Kia Motors and Ssangyong Motor was hit by a four-hour morning shutdown.

Hyundai's union reportedly said it would stage another full-day strike on Wednesday.

Workers there have demanded a 10.48% wage hike, AP said, and they also asked that contract workers be guaranteed pay amounting to 80% of regular salaries, and that management set aside 5% of the company's net profit to establish a welfare fund for contract workers.

Negotiations with Hyundai management broke down earlier this month, the Associated Press noted.

Hyundai estimated its lost production Tuesday at 11,600 vehicles, or 160 billion won ($US139 million), an unnamed company spokesman reportedly told Dow Jones Newswires.

AP said Kia workers are asking for a 10.5% wage increase, and want bonuses to be increased to 800% of the current salary, from the present level of 700% - the Kia union is also calling for union participation in management, as well as equal treatment for contract workers.

Kia reportedly said Tuesday's work stoppage will likely cost it 5,300 vehicles, or 74 billion won ($US64.3 million).

Ssangyong's union wants a 10.5% basic wage hike and bonus increase, according to the Associated Press, and also wants management to consult the union before establishing overseas plants, and a job security guarantee for contract workers.

The Ssangyong union and management are to hold their 10th negotiation session on Thursday, AP said.

GM Daewoo Auto & Technology told Associated Press its operations would be halted for two hours on Tuesday because of a partial strike there.