By Yi Whan-woo

South Korea denounced Japan for making repeated sovereignty claims on its easternmost islets of Dokdo in a defense white paper released by Tokyo on Tuesday.

Japan's Ministry of Defense has stated that Dokdo, which it refers to as Takeshima, has been part of its territory for 10 straight years from 2005 in its annually published report.

The Ministry of Foreign Affairs here asked that Tokyo withdraw its claim to the islets, saying that such arguments are "not acceptable."

"The government cannot accept Japan's claim and we urge Tokyo to refrain from repeating its assertion," the ministry said in a statement.

"The Japanese government proposes to improve Seoul-Tokyo ties on the one hand, while taking actions that could damage such ties on the other.

"And Japan should bear in mind that South Korea-Japan relations will continue to sour for as long as it makes unjustifiable claims on Dokdo."

Tokyo's latest announcement about the island located in the East Sea came amid strained relations between the two countries following a series of disputes over historical issues.

One statement in the white paper reads, "Japan confronts unresolved territorial issues over the Northern Territories and Takeshima, both of which are inherent parts of Japanese territory". This refers to Japan's ongoing territorial dispute with Russia and South Korea, respectively.

"On top of this, there has been a tendency in recent years toward prolonged ‘gray-zone' situations, which could develop into grave situations," it added.

South Korea has held sovereignty over Dokdo since its independence from Imperial Japan in 1945.

Japan once acquired Dokdo during the 1910-45 colonial rule of the Korean Peninsula.

The annual white paper summarizes Japan's defense policy in relation to the geopolitical landscape in Northeast Asia and other parts of the world. This year, it underscored increases in China's military expenditure and continuing military threats from North Korea.