The United Nations is planning to consider later this year the scientific validity of a claim by China that a group of disputed islands in the East China Sea are part of its territory, although Japan says the world body should not be involved.
Tensions over the uninhabited islands - located near rich fishing grounds and potentially huge oil-and-gas reserves - flared after Japan's government purchased them from a private Japanese owner in September, sparking violent anti-Japanese protests across China and a military standoff.
Taiwan also claims the islands, known as the Diaoyu islands in China, the Senkaku islands in Japan and Tiaoyutai in Taiwan.
In a submission to the U.N. Commission on the Limits of the Continental Shelf, China claims that the continental shelf in the East China Sea is a natural prolongation of China's land territory and that it includes the disputed islands.
Under the U.N. convention, a country can extend its 200-nautical-mile economic zone if it can prove that the continental shelf is a natural extension of its land mass. The U.N. commission assesses the scientific validity of claims, but any disputes have to be resolved between states, not by the commission.
China said the "Diaoyu Dao upfold zone" - the islands - is located between the East China Sea shelf basin and the Okinawa Trough. "The Okinawa Trough is the natural termination of the continental shelf of (the East China Sea)," it said.
China also told the commission that it was still negotiating with other states on the delimitation of the continental shelf.
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"Recommendations of the commission with regard to the submission will not prejudice future delimitation of the continental shelf between China and the states concerned," said the executive summary of China's submission published on the commission's website.
The commission said consideration of China's claim would be included in the provisional agenda of a meeting of the body due to be held in New York from July 15 to August 30.
In a letter to the commission, Japan's U.N. mission argued that China's submission should not be considered.
"There is no doubt that the Senkaku Islands are an inherent part of the territory of Japan in light of historical facts and based upon international law. The Senkaku Islands are under the valid control of Japan," it said.
The islands were put under Japan's control in 1895 and were part of the post-World War Two U.S. military occupation zone from 1945-72. They were then returned to Tokyo by U.S. authorities in a decision China and Taiwan later contested.
China responded to Japan's letter by calling Tokyo's claim to the islands "illegal and invalid."
"Diaoyu Dao and its affiliated islands have been inherent territory of China since ancient times," its U.N. mission said in a letter.
U.S. Secretary of State Hillary Clinton urged China and Japan in September to let "cool heads" prevail in the dispute, but her pleas fell on deaf ears.
After Japan's purchase of the islands, protests in China saw some Japanese businesses looted, Japanese citizens attacked and auto and other Japanese manufacturers reported considerably lower sales in the country.
More recently, Japanese military planes have scrambled numerous times against Chinese planes approaching airspace over the islands. Chinese planes have also been launched to shadow Japanese planes elsewhere over the East China Sea. Patrol vessels from the two countries have also played a tense game of cat-and-mouse in the waters near the disputed islands.