Sales of South Korea-based carmakers dropped to a seven-year low last month, industry data showed Sunday, mainly on the back of a series of labor strikes and the end of tax favors for new vehicle purchases.

According to the data from the Korea Automobile Manufacturers Association, domestic sales of locally produced vehicles came to 108,617 units, with 142,987 units being sold abroad in August.

This brings the total to 251,604, excluding those produced in overseas factories, the monthly data showed.

The figure is the lowest sales since August 2009, when combined sales hit 232,656 units for locally manufactured cars, and is way short of the average 380,000 sold on a monthly basis in 2015.

The automakers include industry leader Hyundai Motor Co., its smaller affiliate Kia Motors Corp. and GM Korea Co., the South Korean unit of U.S. carmaker General Motors Co. The other two are Ssangyong Motor Co., the local unit of Indian automaker Mahindra & Mahindra Lt., and Renault Samsung Motors Co., the local unit of French automaker Renault S.A.

Industry watchers attributed the drop to a series of strikes staged by the two industry leaders: Hyundai and Kia.

Unionized workers of Hyundai Motor staged 14 rounds of partial walkouts between July and August, while their union leaders were locked in heated negotiations over a wage increase.

The watchers also said the decline was partly attributed to the termination of a temporary tax cut on new car purchases on July 30. (Yonhap)