SEOUL, Aug. 29 (Xinhua) -- Sentiment among South Korean businesses over economic situations fell this month on worries about Japan's export curbs, central bank data showed on Thursday.

The business sentiment index (BSI) stood at 69 in August, down 4 points from the previous month, according to the Bank of Korea (BOK).

The figure slipped below 70 for the first time in six months. And the reading below 100 indicates pessimists outnumbering optimists.

The BSI for manufacturers declined 5 points over the month to 68 in August, while the index for non-manufacturers slid 2 points to 70 in the month.

Concerns deepened among manufacturers about Japan's export curbs against South Korea as Japan tightened control last month over its export to South Korea on three materials vital to produce memory chips and display panels, which is the mainstay of the South Korean export.

Japan dropped South Korea off its whitelist of trusted trading partners earlier this month. In response, Seoul took Tokyo off its whitelist of trusted export partners.