Beijing's military accused Tokyo of a "highly dangerous provocation" by interfering in Chinese live-fire drills in the Pacific last week, warning that Japanese lives could be at stake, AFP reports citing a Friday report of the state media.
Japanese ships and aircraft tailed Chinese navy vessels conducting the exercise in the western Pacific ocean, the defence ministry said, according to reports.
"The actions 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 lead to misjudgment and accidental injuries," the state-run China Daily quoted defence ministry spokesman Yang Yujun as saying.
Yang made the comments at the defence ministry's monthly press briefing, which foreign media are barred from attending.
According to China's state-run Global Times, the People's Liberation Army Navy was conducting drills in the western Pacific last Friday when a Japanese warship "broke into the drill zone" and remained in the area for three days.
An unspecified number of Japanese aircraft also entered the area several times, tailing and monitoring the Chinese vessels, the report said.
The ministry had lodged a "solemn representation" over the action, it added.
China gave advance warning through the International Maritime Organization on October 23 of its plans to conduct the drills, the Global Times said.
Tokyo took issue with the complaint, with Deputy Chief Cabinet Secretary Katsunobu Kato saying: "Japan is conducting warning and surveillance activities in the surrounding waters appropriately.
"It is not true that Japan interfered with military drills by Chinese naval vessels," he said, adding Tokyo had already made its case to Beijing.
The furious Chinese response -- and implicit threat -- marks a further deterioration in their already fraught relationship, which has soured in recent years as the two Asian giants exchange tough rhetoric over disputed islands in the East China Sea and Japanese leaders' visits to a controversial Tokyo war shrine.
The latest escalation comes a week after Beijing's defence ministry said that any Japanese move to shoot down Chinese drones would amount to an "act of war".
Also last week, Japanese Prime Minister Shinzo Abe warned China over its maritime activities, saying in a speech to Japan's Ground Self-Defense Force troops: "We will demonstrate our intention not to allow a change in the status quo."
"We must conduct surveillance and intelligence activities for that purpose," Abe said in his address, according to Japan's Kyodo news service.