China's sovereignty over the resource-rich area in East China Sea has not been undermined by the agreement with Japan to explore it jointly for gas.

Vice-Foreign Minister Wu Dawei said this yesterday, rubbishing media reports to the contrary.

Making an unusual appearance at the Foreign Ministry's regular news briefing, he said: 'The consensus reached by China and Japan will not harm China's sovereignty and jurisdiction over the East China Sea."

And "China (still) doesn't recognize the 'median line' that Japan claims".

China's "sovereignty" over the Diaoyu island chain is "indisputable" too, Wu said.

After years of talks, the two countries agreed on June 18 to jointly explore Chunxiao, China's largest offshore oil and gas field, in accordance with Chinese laws.

Elaborating on the concept of "joint exploration", a key term in the agreement, Wu said: "It means putting aside sovereignty disputes. We've chosen an area acceptable to both sides for joint development."

"These are all transitional arrangements because we cannot settle the demarcation problem in a short time."

"The most important point is that Chunxiao has to be explored in accordance with the Chinese law," he said, referring to China's laws on exploring offshore petroleum resources with foreign enterprises.

"That also means Chunxiao is within China's sovereign sphere. We must make this clear."

The historic consensus is the result of "better conditions for communication" after the warming up of bilateral ties, he said, citing exchange of visits between top leaders and Japan's quick and charitable response to the May 12 earthquake.

The agreement proves that the two sides are "sincere" to solve sensitive bilateral issues through dialogue, he said. "I believe we can solve other sensitive and complex issues too."

Liu Jiangyong, a senior scholar on Japan studies at Tsinghua University, said the biased reports in a section of the Japanese media have created all the trouble because "each side has made concessions".