April 17 (Bloomberg) -- China's closure of a disputed area in the East China Sea to international shipping may violate the United Nations Convention on the Law of the Sea, Japan's government spokesman said.

Ships passing by an area that straddles the median line between China and Japan should keep a distance of 1 sea mile from Chinese vessels laying submarine pipelines and cables in the so- called Pinghu gas fields, the Chinese maritime authority said in a March 1 notice on its Web site. The order is in place until Sept. 30, according to the notice.

The move by China ``may infringe our sovereign right, and violate the UN convention,'' Japan's Chief Cabinet Secretary Shinzo Abe said today in Tokyo. ``We will take appropriate response after confirming the facts.''

Pinghu is a city on the eastern Chinese coast in Zhejiang province. The gas fields named after the city belong to the China National Offshore Oil Corp., a state-owned company.

Japan considers the median line as a separation of the 200- nautical mile exclusive economic zone from China. The disputed area extends into Japanese waters, Japan's Kyodo News Agency said late Saturday, citing Japanese embassy officials. The Japanese government is inquiring with China over the situation, Kyodo reported.

To contact the reporter on this story: Keiichi Yamamura in Tokyo at kyamamura@bloomberg.net

Last Updated: April 17, 2006 00:08 EDT