BEIJING - China's Foreign Ministry here Tuesday lodged solemn representations and a strong protest to Japan over its illegal navigation in waters around the Diaoyu Islands.

Hua Chunying, the ministry's spokeswoman, told a daily press briefing that China's marine surveillance authorities have dispatched a fleet of eight law enforcement ships on a patrol mission.

"So far as we know, boats with Japanese right-wing activists aboard have already withdrawn from China's sovereign waters around the Diaoyu Islands," Hua said.

Also on Tuesday, Chinese Ambassador to Japan Cheng Yonghua protested Japan's intrusion into waters of the Diaoyu Islands and demanded that all Japanese ships leave the waters immediately, according to the Chinese embassy in Japan.

Cheng lodged the protest during his meeting with Japanese vice Foreign Minister Chikao Kawai and rejected Japan's protest over Chinese surveillance ships entering into the waters, said the embassy on its website.

Cheng emphasized the Diaoyu Islands and its surrounding waters are Chinese inherent territories and the Chinese surveillance ships were on regular patrol duty.

Earlier Tuesday, several Japanese boats were spotted in waters around the islands and about eight Chinese marine surveillance ships monitored the intruding Japanese ships from different angles, according to China's State Oceanic Administration.