Hyundai Motor employees in South Korea have rejected a tentative wage agreement between management and their union in a move business newswire Bloomberg said may affect the automaker's efforts to reverse 10 consecutive quarters of profit decline.

Some 78% of 45,777 union members eligible to vote turned down a deal reached earlier this month which included a monthly wage increase of KRW58,000 (US$51) and incentives, Hyundai Motor told Bloomberg.

The rejection was the first time since 2008 unionised workers at the country's largest automaker voted down a wage deal, Jang Chang Yeol, a union spokesman, told Bloomberg.

"Many of our members didn't agree with the tentative deal since they felt the wage benefits were less generous than last year's wage package," Jang said. Negotiations would resume in September, he said.

Bloomberg noted a failure to reach an agreement would set the automaker up for more strike action and loss of production at a time when demand at home and in emerging markets remained lacklustre, potentially leading Hyundai to miss its sales target for the second consecutive year. A series of strikes that started in July had led to a production loss of 65,500 cars with a value of KRW1.47 trillion, according to the company.