South Korea summoned a senior Japanese diplomat here Monday to protest a Japanese prefecture's hosting of an annual event to promote its territorial claim to Seoul's easternmost islets of Dokdo.
  

Japan's Shimane Prefecture, which claims administrative sovereignty over the rocky islets, observed the so-called Takeshima Day event on Sunday. A Japanese vice-minister-level official was sent to this year's ceremony, prompting a strong protest from South Korea.
  

The prefecture has held the event on Feb. 22 since 2005, and Takeshima is the Japanese name of the islets.
  

Seoul's foreign ministry said it called in Kenji Kanasugi, a minister at the Japanese Embassy in Seoul, to deliver a strong protest over the ceremony.
  

Briefly after the Sunday event in Japan, the foreign ministry strongly condemned the move, labeling it as a "historically regressive behavior."  
  

The rocky outcroppings, which lie closer to South Korea than Japan in waters between the neighbors, have been a nagging source of diplomatic feud between them.
  

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)