South Korea condemned Japan's dispatch of a senior government official Monday to a local event aimed at publicizing its claim to Dokdo, a pair of outcroppings in the East Sea.
In a statement, the Foreign Ministry stressed that Dokdo is South Korea's territory historically, geographically, and under international law.
It urged Japan to immediately stop such a territorial provocation and "humbly face up to its history" of aggression and imperialism.
Earlier in the day, the Shinzo Abe administration sent Yasuyuki Sakai, parliamentary vice minister of the Cabinet Office, to the controversial yearly event hosted by the Shimane Prefecture.
In 2005, the western prefecture, which claims administrative sovereignty over the islets, designated Feb. 22 as "Takeshima Day."
Takeshima is the Japanese name for Dokdo.
South Korea views the Abe government's commitment to the day as undermining the burgeoning mood for a new bilateral relationship between the neighboring nations.
The two sides struck a deal in December ending decades-long disputes over Japan's sexual enslavement of Korean women during World War II.
The ministry said Tokyo should make joint efforts to open the way for new ties with Seoul.
South Korean civic groups also staged a series of protest rallies in Seoul.
Over 100 South Koreans who belong to civic groups promoting South Korea's sovereignty over Dokdo held a joint press conference in front of the Japanese Embassy, urging Tokyo to scrap Takeshima
Day and Japanese textbooks that distort history.
The civic groups also demanded the South Korean government nullify the 1998 fisheries agreement signed by Seoul and Tokyo, which designated a part of the East Sea where the two countries'
Exclusive Economic Zones (EEZ) overlap each other as a joint fishing zone.
Japan's claim to Dokdo, which lies in waters between the two nations rich in fish and natural resources, dates back to Japan's colonial rule of the Korean Peninsula in the early part of the 20th century. (Yonhap)