The Ministry of National Defense said on Thursday that a Japan Maritime Self-Defense Force ship intruded into a Chinese military exercise in the open sea and remained there for three days despite warnings China issued through the International Maritime Organization.

The Japanese warship entered the exercise area in the west Pacific at 10:41 am on Oct 25 and stayed until 7:32 am on Oct 28, Yang Yujun, the ministry's spokesman said during a monthly news briefing.

He added that Japan also sent reconnaissance craft and ships to follow the Chinese ships.

"The above acts of the Japanese ships and planes not only interfered with our normal exercises but also endangered the safe navigation of Chinese ships and planes, and might have even lead to accidents, including misjudgment and injuries," Yang said.

"This is a highly dangerous provocation. The Chinese Defense Ministry has made solemn representations to the Japanese."

The drill, which began on Oct 24 and will last until Nov 1, is the first open-sea drill in which maritime and air forces from all three of China's fleets have taken part.

Chinese authorities had previously publicized the exercise areas via international maritime organizations in accordance with international practice, alerting foreign vessels and planes to take precautions.

The exercise is expected to improve high-sea combat abilities and hone strategies for utilizing information technology.

The country's three fleets - the North China Sea Fleet, the East China Sea Fleet and the South China Sea Fleet - all took part in the exercise.