SEOUL (AFP) - South Korea on Tuesday slammed Japan's "ludicrous" reassertion of its claim to a set of disputed islets in a new defence white paper, warning it would further strain relations.

The white paper released in Tokyo briefly alluded to a set of territorial disputes, including one with South Korea over a group of islands in the East Sea (Sea of Japan).

The South Korea-controlled chain of rocky islets - called Dokdo by Seoul and Takeshima by Tokyo - have been the cause of tensions between the two neighbours for decades.

"The Japanese government repeated the ludicrous claim that Dokdo is its own territory... in its 2014 White Paper," Seoul's foreign ministry said in a statement.

"We find the claim unacceptable and urge Japan to withdraw it," the statement said.

Relations between the two countries are currently at their lowest ebb for years due to various other disputes linked to Japan's 1910-45 rule over the Korean peninsula.

The row over the islands intensified after then South Korean President Lee Myung Bak made a surprise visit there in 2012.