South Korea on Thursday formally rejected Japan's proposal that the two countries ask an international court to settle a bitter row over disputed islands, labelling Tokyo's stance "wrong".
South Korea last week received a "note verbale" -- an unsigned diplomatic missive -- from Japan suggesting that both sides jointly refer the dispute to the International Court of Justice (ICJ) for settlement.
South Korea's reply was delivered Thursday through a Japanese diplomat in Seoul, a foreign ministry spokesman said.
It clarified Seoul's stance that no territorial disputes exist about the South Korean-controlled islands in the Sea of Japan (East Sea), known as Dokdo in Korean and Takeshima in Japan, spokesman Cho Tai-Young told reporters.
"We have made it clear that Dokdo is our own territory in terms of history, geography and international laws... we are not going to the ICJ," he said, calling Tokyo's claim on the island "unfounded and illegitimate".
"We also urge again the Japanese government to realise the wrong ideas it has about Dokdo and to correct them immediately."
Japan Foreign Minister Koichiro Gemba said in a statement that he was "extremely disappointed at the response from South Korea, which has not presented any specific counter-proposal to solve this issue".
In the statement, Gemba said Tokyo will take "appropriate measures" including unilaterally taking the case to the Hague-based court.
Relations between the two sides have deteriorated since South Korean President Lee Myung-Bak paid a surprise visit on August 10 to the islands.
He said his trip, the first by a South Korean president, was intended to press Japan to settle grievances left over from its 1910-1945 colonial rule over Korea.
Lee further angered Japan by saying later that Emperor Akihito must sincerely apologise for past excesses should he wish to visit South Korea.
Japan cancelled a finance ministers' meeting scheduled for this month and said it would review a foreign exchange swap agreement with Seoul, as the rift threatened to spill over into economic ties.
Tokyo has also hinted it could freeze its plan to buy South Korean government bonds. Japan, South Korea and China had agreed in May to hold each other's government bonds.
Japanese Prime Minister Yoshihiko Noda said last week that South Korea was "illegally occupying" the islands, after Seoul sent back his letter addressed to Lee by registered mail without reading it.