South Korea has postponed the timing of submitting a claim to an extended portion of continental shelf in the East China Sea to a United Nations body to sometime "within this year," according to an official Friday.

The foreign ministry had been finalizing details to submit the claim on seabed beyond its exclusive economic zone (EEZ) in the East China Sea to the U.N. Commission on the Limits of the Continental Shelf (CLCS) "as early as this month," but decided that the submission will be made by the end of this year, the ministry official said.

"In accordance with the U.N. Convention of the Law of the Sea, we will submit documents on the outer limit of our continental shelf to the U.N. CLCS within this year," the official told Yonhap News Agency by telephone.

The official told Yonhap on Thursday that the ministry "completed working-level procedures to formally submit the documents to the U.N. CLCS as early as this month," but backpedaled his remarks on Friday, saying the timing had not been fixed.

The official spoke on the condition of anonymity, citing ministry policy.

In the documents to be submitted to the U.N. commission, South Korea is expected to claim that the Korean Peninsula's naturally extended continental shelf stretches to the Okinawa Trough in the East China Sea, a move certain to rekindle a territorial dispute with Japan and China over the extent of their respective EEZs.

The postponement came a day after Japan's Chief Cabinet Secretary Osamu Fujimura reportedly voiced opposition against the South Korean claim.

Also on Thursday, Seoul's foreign ministry spokeswoman Han Hye-jin confirmed that the government will "soon" submit the documents to the U.N. commission," but declined to specify when the formal claim will be made.

"As we stated several times, our basic stance is that our continental shelf stretches to the Okinawa Trough," Han told reporters.

According to the U.N. Convention of the Law of the Sea, coastal nations can claim an economic zone extending 200 nautical miles (370 kilometers) from their shores. In the EEZ, a country is eligible for exclusive rights to the exploration and use of marine resources.

South Korea lodged a similar claim in its preliminary information submission to the U.N commission in 2009.

The 2009 claim immediately sparked a dispute over sea territory demarcation with China, which followed up with its own claim over the Okinawa Trough.

China argued the trough is part of its natural continental shelf extension. It also submitted a claim to Ieodo, which lies in the overlapping part of the two countries' exclusive economic zones and where South Korea has an observation station. Tokyo also claims the Okinawa Trough, which is believed to contain natural gas and oil deposits. (Yonhap News)