(Adds Lexus sales, background)
SEOUL, Sept 4 (Reuters) - Japanese automakers posted sharper sales falls in South Korea in August, industry data showed on Wednesday, hit by a consumer boycott of Japanese vehicles amid a worsening diplomatic row between the countries.
Toyota Motor Corp and other Japanese carmakers saw South Korean sales tumble 57% to 1,398 vehicles in August from a year earlier, steeper than the 17% fall in July.
Japan's decision in July to tighten controls on exports of materials that South Korea uses to make semiconductors and display screens has prompted a consumer backlash in Korea, with consumers boycotting Japanese products such as beer, clothes, vehicles and tours to the neighboring country.
Relations between the two U.S. allies had already soured over South Korean demands for Japanese compensation for South Korean forced laborers during World War Two.
Toyota's South Korean sales fell 59% to 542 in August from a year earlier, while Honda Motor's sales tumbled 81% to 138.
Toyota's Lexus was the top-selling Japanese brand in South Korea, with sales reaching 603 vehicles in August, up 7.7% from year earlier, but down 39% from July. (Reporting by Hyunjoo Jin; editing by Richard Pullin and Stephen Coates)