BEIJING - China National Offshore Oil Corp (CNOOC) said gas production has started from an oil and gas field in the East China Sea.

	A picture taken on September 9, 2005 shows the Chunxiao gas field. [Web]

On an inspection tour at the Chunxiao field last month, a senior government official said the first stage of gas production had begun and urged CNOOC to make good use of its resources, the company's website reported.

"The first phase of Chunxiao oil and gas field has already entered the production stage," Zhang Guobao, vice director of the National Development and Reform Commission, was quoted by the website as saying.

"But inadequate gas usage from downstream users has limited the speed of the oil field's exploration," he added, according to an AFP report.

Japan has disputed China on the maritime boundary that lies between them, and Beijing has insisted its explorations in its East China Sea are within China's territorial waters.

However, Japan has claimed the gas field lies too close to its Exclusive Economic Zone (EEZ) -- a delineation not recognized by China. Japan has also claimed that CNOOC might siphon off resources from deep undersea.

The Japanese foreign ministry could not be reached for comment on Saturday, AFP said.

But Japanese business daily Nihon Keizai Shimbun quoted unnamed foreign ministry sources as saying that Japan has started examining counter-measures against China's development of a gas field. If gas production at Chunxiao is confirmed, Japan will officially protest against China and call for an immediate halt of drilling, it said.

Japan would try to resolve the dispute through dialogue but would step up its measures if China denies its request, the report added.