China's defense ministry has lodged a solemn representation over a Japanese warship's entering of waters where the People's Liberation Army (PLA) Navy was holding live-fire drills, noting the provocative move may have led to unexpected emergencies.

The incident took place during China's naval drills in the open seas of the West Pacific, which runs from October 24 to November 1.

Yang Yujun, the ministry's spokesperson, Thursday told a monthly press briefing that China released information about the drills on October 23 through the International Maritime Organization, reminding foreign ships and aircraft to avoid the area.

However, regardless of China's repeated warnings, a warship from the Japan Maritime Self-Defense Force broke into the drill zone on the morning of October 25, and stayed in the area for three days.

Meanwhile, Japanese reconnaissance airplanes entered the area several times.

The spokesperson said Japanese warships and aircraft also tailed, reconnoitered and monitored the Chinese naval force during their regular passage.

"The deeds of Japanese warships and aircraft not only interrupted our regular drills, but also posed safety hazards to our ships and aircraft. They may have even caused unexpected emergencies such as miscalculations and accidental damage. This is a highly dangerous provocation," Yang said.

Rear Admiral Yang Yi, former head of the Institute for Strategic Studies at the PLA National Defense University, told the Global Times that although monitoring another country's exercise outside the drill zone is not rare, breaking into the zone goes against international common practice.

"Japan intended to detect our radar frequencies and observe our techniques and tactics. Normally, if the Chinese navy accidentally hit the Japanese ship, Japan would have to take the blame, because it violated international practice by breaking into the drill zone," he said.

China demands Japan reflect on the incident and take concrete steps to correct its wrongdoing, said the spokesperson. "Or else, Japan should accept all the consequences," he warned, adding China reserves the right to take further action.

Bilateral ties between Beijing and Tokyo soured after Japan's so-called nationalization of the Diaoyu Islands in the East China Sea in September 2012, with suspension of meetings between top leaders and declining trade figures.

Since early this year, growing tensions between the two militaries have led many to assess the possibility of a confrontation.

In January, Tokyo accused Chinese naval ships of locking fire-control radar on Japanese ships and planes, a claim Beijing blamed as "stirring up antagonism."

Recently, a Kyodo News report said Japan drafted plans to shoot down foreign drones that "encroach on its airspace" if warnings to leave are ignored, an apparent reference to Chinese drones.

Japan's hawkish Prime Minister Shinzo Abe also irked China by telling the Wall Street Journal he envisions a resurgent Japan taking a more assertive leadership role in Asia to counter China's power. On Sunday, Abe told a military review that Japan will carry out more surveillance and information gathering on China.

Yang Yujun Thursday regarded such statements by Japan as "distorting the facts" and "overrating itself."

Liu Jiangyong, vice dean of the Institute of Modern International Relations at Tsinghua University, told the Global Times that the possibility of accidentally sparking a conflict between China and Japan in the waters and airspace have been rising, as Japan's tailing and close-distance reconnaissance over the Chinese military is expected intensify.

While the Chinese naval drills in the West Pacific conclude on Friday, Japan is scheduled to launch an 18-day large-scale exercise in Okinawa and Kyushu on Friday, including a drill on capturing an island.

 "The Abe administration no longer sees its relationship with China as a strategic partnership of mutual benefits. By using the Diaoyu Islands dispute, he seeks to draft a new National Defense Program Guidelines and Japan's first-ever national security strategy by the end of this year," Liu said.