South Korea's ruling Saenuri Party denounced Japan's move to take the issue of Dokdo to the International Court of Justice as an act of imprudence Sunday, calling for Tokyo's full repentance for its brutal colonial rule of Korea.

A day after South Korean President Lee Myung-bak made an unprecedented visit to the South Korean islets, long claimed by Japan as its own, Tokyo said Saturday it was considering asking the international court to resolve the issue.

Calling the move an act of "imprudence," Hong Il-pyo, a spokesman of the party, said in a statement that Japan's "preposterous" claim over Dokdo, a move far from a sincere repentance for its colonial past, has raised Koreans' ire.

Hong also cited the Japanese attempt to distort history in school textbooks and Tokyo's refusal to address long-running grievances of elderly Korean women forced into sexual slavery for Japanese troops during World War II as other signs Japan has not fully repented for its past.

"We denounce such attitudes by Japan. And if it continues to lay claim over Dokdo, we cannot but take it as a refusal to abandon Japan's will toward invading Korean territory," Hong said.

Lee became the first South Korean president ever to visit the islets, which lie closer to South Korea in the body of water between the Korean Peninsula and Japan, underscoring the nation's territorial control of Dokdo that has long been a thorn in relations between the two countries.

South Korea reclaimed its territory, including Dokdo, when it regained independence from 1910-45 Japanese colonial rule. South Korea has kept a small police detachment on Dokdo since 1954. (Yonhap News)