Scores of South Koreans assembled in central Seoul on Sunday to denounce Japan for holding a ceremony that promotes Tokyo's territorial claim over South Korea's easternmost islets of Dokdo.

In 2005, Japan's Shimane Prefecture, which claims administrative sovereignty over the islets, designated Feb. 22 as a day to promote Takeshima, the Japanese name for Dokdo. Since then, Shimane has hosted various programs to strengthen its territorial claims to the islets on this day.

Tokyo sent a vice-minister-level official to this year's ceremony as a government representative, marking the third year in a row that it has sent a ranking official to the controversial event.

Some 150 South Koreans, who belong to a civic group promoting South Korea's sovereignty over Dokdo, gathered in front of the Japanese embassy here to call for Tokyo to cancel the designation.

"Japan should annul the designation of Takeshima Day," the civic group said. "In addition, Tokyo should immediately stop the annual event and attempts to distort history through textbooks."

"Japan, despite knowing very well that Dokdo is our territory, has tried to take the islets away from us every year. They even chose a textbook that teaches (such nonsense) to their future generations."

A 51-year-old man, who claimed to be a member of a group that promotes South Korea's sovereignty over the islets, threw a plastic bottle filled with filth at the embassy. He was taken away by the police, who believe he has carried out similar acts in the past.

The rocky outcroppings, which lie closer to South Korea than Japan in waters between them, have been at the center of a diplomatic row since Japan's colonial rule of the Korean Peninsula in the early part of the 20th century.

South Korea has rejected Japan's claim to Dokdo since the country regained its independence from Japan's 1910-45 colonial rule and reclaimed sovereignty over its territories, including Dokdo. (Yonhap)