Diplomats involved in Sino-Japanese negotiations on their maritime border dispute say the neighbors have traded proposals to cooperate in developing resources in the East China Sea.

Japanese and Chinese diplomats on Wednesday confirmed that their governments are discussing joint development of maritime resources in the disputed waters of the East China Sea.

Liu Jinsong

Liu Jinsong, first secretary at the Chinese Embassy in Japan, says that Beijing and Tokyo have made recent counterproposals on how and where to conduct joint development programs. He made the comments at a media luncheon also attended by a Japanese diplomat involved in the talks on the disputed area.

"Both sides are agreeing not to leak the information for that, but I still want to leak some information that there is," he said. "Both sides are ready to propose some proposals. We are very careful and serious in studying each others' proposals."

Sino-Japanese diplomatic ties have chilled in the past few years in part because of maritime boundary disagreements. Their exclusive economic zones overlap in the East China Sea.

China has angered Tokyo by exploring undersea gas fields immediately outside Japan's claimed zone. Japan contends that China is drilling so close to the line that it could be sucking undersea resources from the Japanese side. Complicating matters is the fact that Beijing and Tokyo have yet to agree on the precise area in dispute.

Also speaking at the luncheon was Yukiya Hamamoto, the deputy director of the Japanese Foreign Ministry's international legal affairs bureau. He says the lack of a clearly marked area is a problem.

Yukiya Hamamoto

"Obviously joint development is something which is done in the disputed area. If we have some arguments on where is the disputed area that obviously would make some difference to the outcome," said Hamamoto.

The Chinese, however, point out they already have joint development agreements with Russia, Vietnam and the Philippines in areas where maritime sovereignty is disputed.

Liu also contends that despite concern in Japan that Beijing is acting provocatively, its military has been restrained in not asserting China's territorial claims.

"We have not sent our warships or the war planes to that area, even [though] we think it's all right," said Liu. "I think right now we restrain ourselves that we have rights to make some drill [do some drilling] in the disputed area."

The Chinese diplomat says he believes that Japan also will practice such restraint, despite calls by some here for Tokyo to dispatch military ships to the disputed waters in response to China's gas exploration.