Feb. 22 (UPI) -- A North Korean university condemned Japan for claiming disputed islets in the East Sea, or Sea of Japan, is part of Japanese territory, the same day Japanese politicians observed "Takeshima Day."
South Korea also protested the Japanese policy on Monday.
Kim Il Sung Broadcasting University stated on its online site Japan's "ambition to rob" the Dokdo Islets reflects its policy of "modern-day revisionism."
North Korea previously has condemned Japan for laying claim to Dokdo, which is under South Korean administration. Japan's Shimane Prefecture began to observe Takeshima Day in recent years.
According to Japanese paper Sankei Shimbun on Monday, Shimane Gov. Tatsuya Maruyama held a ceremony in the prefectural capital of Matsue to declare Dokdo part of Japan's sovereign territory. Maruyama reportedly said there is "ongoing movement to realize the Korean occupation of Takeshima," or Dokdo.
North Korea has supported South Korean claims to the territory. According to the statement on the North Korean university site, Japan annexed Dokdo in the early 20th century during a period when it sought dominion over the Korean Peninsula. Japan colonized the Korean Peninsula from 1910 to 1945, but ceded the country after surrendering to the United States and allies.
Japan's claims to Dokdo represent "a modern-day colonial extortionist act, the most vicious and reactionary ideas that can never be permitted," Kim Il Sung Broadcasting University said.
North Korea's accusations against Japan of stoking right-wing nationalist sentiment come at a time of ongoing friction between Tokyo and Seoul.
On Monday South Korea's foreign ministry summoned Hirohisa Soma, deputy head of the Japanese Embassy, to protest Takeshima Day, Korea Economic Daily reported. Last year Seoul also filed a complaint with Tokyo's diplomats, when the Japanese government laid claim over Dokdo.
Japanese Prime Minister Yoshihide Suga did not attend the ceremony in Shimane Prefecture on Monday, but his subordinate, Cabinet official Yoshiaki Wada, attended the regional event.
South Korea and Japan have yet to resolve historical and territorial disputes or improve ties that declined under ex-Prime Minister Shinzo Abe and South Korean President Moon Jae-in. Moon said last week Japan should "sincerely apologize" for wartime crimes.