South Korea denounced Japan's repeated claim to Seoul's easternmost islets of Dokdo on Tuesday, calling it an "unjustifiable" move that would not help improve already chilled bilateral relations.

Seoul's criticism came as Japan's Cabinet approved Tokyo's defense white paper for 2014 earlier in the day, in which Japan laid claim to the East Sea islets. Japan has asserted its claim to Dokdo in its defense report for the past 10 years.

The Dokdo islets, which lie closer to South Korea than Japan in waters between the two countries, have been a thorny bilateral issue. South Korea keeps a small police detachment on the islets.

South Korea has rejected Japan's claim to Dokdo as nonsense because the country regained its independence from Japan's 1910-45 colonial rule and reclaimed sovereignty over its territories, including Dokdo and many other islands around the Korean Peninsula.

"The South Korean government cannot accept Japan's unjustifiable claim and gravely urges Japan to rescind it and prevent a recurrence of similar activities," Noh Kwang-il, spokesman at Seoul's foreign ministry, said in a statement.

"Japan should keep in mind that if it continues to lay claim to Dokdo, improvement in the Seoul-Tokyo relations will be far away."

The government said it plans to summon a senior diplomat from the Japanese Embassy in Seoul later in the day to lodge a protest against the latest move.

Relations between Seoul and Tokyo have reached their lowest ebb in recent years due to Japan's stance on historical grievances and its territorial claims to Dokdo.

Japan's move may deal a further blow to the already-icy bilateral ties at a time when the two countries are mulling holding a foreign ministers' meeting on the sidelines of an Asian security forum to be held in Myanmar on Sunday.

Seoul has said that nothing has been decided on the issue, but added that it is open to dialogue if Japan makes a request.

Seoul's foreign ministry has been ramping up efforts for an international publicity campaign against a similar move waged by Japan to strengthen its ownership of the islets.

Korea's move is designed to show that Dokdo is South Korean territory in terms of history, geography and international law.

Seoul has allocated 4.84 billion won ($4.69 million) in its budget for next year to publicize its sovereignty of the volcanic outcroppings. (Yonhap)