China reiterated on Saturday that a gas field near a disputed part of the East China Sea was part of its territory, despite Japanese protests.
East Asia's two largest economies struck a deal in June last year to end a lingering spat over Chinese undersea gas fields which, Japan said, may extend into its exclusive economic zone.
But Japan has complained about China's development of the nearby Tianwaitian gas field, which Tokyo contends should be untouched before talks settle its status.
"The Tianwaitian field is located in China's exclusive economic zone," Chinese Foreign Minister Yang Jiechi told a briefing in Beijing Saturday.
"It has nothing to do with the principled common understanding between the two countries on the East China Sea issue," he said.
Japan said in January it "cannot accept" China's development of the Tianwaitian field and closed-door meetings between the two nations in Tokyo the same month failed to make progress.
Under last year's deal, Japan agreed to invest in one field in the area and jointly develop another.
The June agreement stipulated that the two nations would continue talks over other gas fields. But China continues to insist that it has the right to develop them.
"The principled common understanding reached between the two countries on the issue of the East China Sea is a reflection of the improvement and development of China-Japan relations," Yang said.
"I believe both sides should honour the spirit of the principled consensus and create necessary conditions for implementation."
