Korea’s auto workers, represented by some of the country’s most powerful labor unions, are putting in hours beyond legal limits, the Labor Ministry said Sunday.

The ministry’s on-the-spot checks found that all five carmakers operating in Korea, including the largest Hyundai Motor, had their employees work in excess of the 12 hours of weekly overtime that the law permits.

Their working hours per week averaged 55, about 14 hours longer than the country’s industry average. The five carmakers are Hyundai Motor and its affiliate Kia Motors, Renault Samsung, GM Korea and Ssangyong Motor.

“The automotive industry is failing to raise its labor productivity, because it sticks to a system of long working hours and high compensation under agreements between management and labor unions,” said Labor Minister Lee Chae-pil.

Ordering the companies to correct the illegal practice immediately, the minister warned that they will be given no leniency if caught again.

Carmakers, however, complained that overtime is virtually the only way for the firms to adjust their production to any increase in demand, because of the country’s rigid labor market and powerful labor unions.

“Strict enforcement of the labor rules, without consideration of the unique labor situation and the car industry’s characteristics, could hurt Korean carmakers’ global competitiveness,” the Korea Automobile Manufacturers Association said in an e-mailed statement.

The ministry’s action comes as the government seeks to reform labor practices in the automotive industry, which revolve around a draconian two-shift production system that divides its workforce into a dayshift and a nightshift.

Automotive labor unions also resist any change to the current two-shift work system, preferring fatter paychecks to shorter hours.

Ministry officials said most foreign carmakers run two shifts during the daytime only, or three shifts for the whole day.

By Lee Sun-young (milaya@heraldcorp.com)