Anti-Japan protesters lashed out at a South Korean employee of the Japanese Consulate General in Busan earlier this month as he stepped outside to photograph the protest, sources said Sunday.
Japanese consular officials reported the March 1 assault to South Korean police and told them to take steps to prevent it from happening again.
The incident took place on the anniversary of the 1919 March 1st Movement, which sparked the Korean independence movement against Japan, which had annexed the Korean Peninsula in 1910 and was trying to wipe out its language and culture.
The sources said several protesters surrounded the consulate employee while he was taking photos of them, adding that he received a scrape on his right hand during the altercation.
South Korean activists also staged an rally in front of the Japanese Embassy in Seoul on March 1.
Ties between Japan and South Korea are under severe strain over historical issues stemming from Japan's 1910-1945 colonial rule and a bitter territorial dispute over two tiny Korean-held islets in the Sea of Japan, which South Korea calls the East Sea.
The rocky islets situated roughly halfway between the countries are called Dok-do by South Korea and Takeshima by Japan.