It was perfectly normal for Chinese ships to conduct research work in the area around the Diaoyu Islands, said Chinese Foreign Ministry spokeswoman Jiang Yu here Tuesday.

"China, through diplomatic channels, has expressed dissatisfaction over Japan's attitude toward this issue," Jiang told a regular press conference.

The 3,235-ton Dongfanghong No. 2 was reported Sunday morning to be some 30 kilometers west-northwest of Uotsuri, the main isle of the Diaoyu Island group in the East China Sea.

When asked to comment on the issue, Jiang said the Diaoyu and surrounding islands have been Chinese territory since ancient times, and China's sovereignty over them is indisputable.

China could not accept Japanese claims that the Diaoyu Islands are Japanese territory, she noted.

It was China's legitimate right to conduct research work in the waters near the Diaoyu Islands, and no notice of such research work was required, Jiang said.

Officials with the Chinese Foreign Ministry in charge of Asian affairs summoned Japanese diplomats on Monday, and lodged a complaint with them over Japan's approach to the issue.

Source: Xinhua