A top union official at Hyundai Motor has said he will resign over what is believed to be a dispute with other unionists over changes in the shift system and working hours.

Yoon Hae-mo called a press conference yesterday morning to announce his resignation but the union postponed the announcement until after a meeting today, union officials told the Korea Herald.

If Yoon does quit, it would be the first time a Hyundai union leader has stepped down during the annual wage negotiations, the paper noted.

His resignation would disrupt this year's wages talks, which are still in an early stage.

"If the union leaders decide to step down, new leaders will have to be elected and that could significantly delay this year's wages negotiations," said Hyundai official told the Korea Herald.

"As the situation is still uncertain and the final decision will not be made known until tomorrow, the exact impact such developments will have on the negotiations remains unclear."

According to the report, Yoon is thought to have disagreed with other members of the opinion group to which he and other union leaders belong to concerning changes to the shift system and working hours. However, Hyundai officials could not confirm the exact cause of the disagreement among union members.

The new two-shift system would reduce working hours and stop production after midnight.

Although the new system would reduce Hyundai's daily production time by more than four hours, the union is demanding that the pay is maintained at current levels.

According to news reports, Yoon is also said to have disagreed with the group's decision to dismiss a mid-level union official.