Japanese authorities the day before protested to China over Beijing's unilateral development of natural resources in the East China Sea, Asahi reported Saturday, citing a Japanese Foreign Ministry statement.

"It is extremely regrettable that China is proceeding with its unilateral development activity, even though it is in the west side of the equidistance line between Japan and China," the Japanese ministry said in a statement.

The agency reminded that China continues to conduct such activities despite the agreement of the two countries on cooperation in the waters of the region dated 2008.

Asahi reminds that in the East China Sea there is no officially established border between Japan and China. In turn, China has built more than a dozen drilling platforms at gas fields west of the line, which is considered in Tokyo as the demarcation zone of economic interests of the two countries.

At the same time, Japanese authorities have previously recorded China's transportation to the region of the basis for another drilling platform.

The dispute between China and Japan in the East China Sea arose in connection with the discovery of offshore gas fields there and the beginning of their development by the Chinese side.

In addition, Tokyo and Beijing have a territorial dispute over the Japanese-controlled Senkaku Islands (Chinese: Diaoyu) in the East China Sea.