TOKYO, Nov. 1 (UPI) -- Japan said China's decision to develop new gas fields in disputed areas of the East China Sea is "extremely regrettable," after Tokyo discovered a Chinese drilling vessel near existing fields.
Japanese Foreign Minister Fumio Kishida told reporters Tuesday the government has evidence of a "mobile oil prospecting ship" that had anchored near a Japan-supported median line between the China and Japan coasts, the Sankei and Nihon Keizai newspapers reported.
"It is extremely regrettable that China is maintaining its activities toward the unilateral development of the area despite our repeated protests," Kishida said, according to Kyodo news agency.
Japan has called for the establishment of the median line that is situated halfway between the coast of Okinawa and the Chinese mainland.
According to Sheila A. Smith, a senior fellow for Japan Studies at the Council on Foreign Relations, the United Nations Convention on the Law of the Sea cannot be applied mandatorily in the 360-nautical-mile-wide East China Sea because the area falls short of the 400 nautical miles required for enforcement.
Japan and China have been locked in a dispute over how to share the East China Sea because Tokyo supports the median line while China wants to claim an exclusive economic zone based on its extended continental shelf, according to Smith.
Past attempts to cooperate on resource development have also failed.
A 2008 Japan-China agreement on oil and gas exploration at the Shirakaba or Chunxiao Oil and Gas Field was suspended in 2010 due to history and territorial disputes, according to South Korean news service News 1.
China has continued with oil and gas projects despite Japanese protests.
Tokyo says China is now drilling at 17 different locations in the East China Sea.