HONG KONG • Japan and South Korea have scrambled their fighter jets after spotting Chinese warplanes flying over the waterway dividing the two neighbours.

The Chinese aircraft did not violate Japanese airspace but flew within South Korea's air defence identification zone (ADIZ), reported the South China Morning Post, citing Japan's Ministry of Defence.

On Monday, Chinese state-run media criticised Japan for drawing public attention to the operation.

It was "normal routine training, and Japan panicked and overreacted, which shows Japan may have wanted to hype the event and act as a troublemaker", The Global Times newspaper quoted Beijing-based air defence expert Fu Qianshao as saying.

Apart from six H-6 bombers, the Chinese aircraft that flew over the East China Sea and Sea of Japan included a Shaanxi Y-8 early-warning plane and a Shaanxi Y-9 intelligence-gathering plane.

South Korea's Yonhap news agency reported late on Monday that the Chinese planes flew into the Korean ADIZ near Ieodo, a submerged rock located off the southern coast of Jeju Island, several times from 10am to 3pm on Monday. China's own ADIZ overlaps partially with that of South Korea and includes the Ieodo rock which is claimed by both sides. It is known as Suyan to China.

An unnamed government source told Yonhap the South Korean jets sent a warning signal to the Chinese planes and its air force delivered warning messages to the Chinese side.

Similar aerial incidents have occurred between China and its neighbours in recent months.

This was not the first time Beijing flew jets over the contested region in the Korea Strait.

China dispatched several warplanes and aircraft to the area in 2013, and most recently in August last year in what was described as a "muscle-flexing exercise" to show Beijing's displeasure over Seoul's planned deployment of a US anti-missile defence system.

Last month, China's first aircraft carrier Liaoning, accompanied by three guided-missile destroyers and two frigates, raised alarm bells in Tokyo after it was spotted cruising into the Western Pacific Ocean for the first time via the waterway between Okinawa and Miyako Island.

Japan has said it would keep a steady eye on the "expanding and increasing" actions of the Chinese military in the area, according to the Japan Times.