By Heekyong Yang

SEOUL (Reuters) -Hyundai Motor Co and a union representing its South Korean workforce on Monday sealed a wage deal that will boost annual pay by about 12%, avoiding a strike and production losses at the company's biggest manufacturing base.

The union, one of the biggest in South Korea with more than 44,000 members, said on Monday that a total of 58.81% of its voting members had approved the tentative agreement reached last week.

Unionised workers voted last month for a possible strike over demands for higher wages, a performance bonus and an increase to the mandatory retirement age to 64 from 60.

The union demand to increase the retirement age - which would have allowed workers to stay in their jobs, reducing reliance on the pension system, for longer - was not accepted.

Workers at Hyundai Motor, the No.3 global automaker by sales with its affiliate Kia Corp, last went on strike in 2018.

Unionised workers at Hyundai in South Korea held a four-hour strike for one day in July in support of a general strike, but it was not related to the union's wage negotiations with the management.

(Reporting by Heekyong Yang; Editing by Andrew Heavens and Jan Harvey)