Beijing says it is setting up an "air defence identification zone" over an area that includes islands controlled by Japan but claimed by China, in a move that could inflame the bitter territorial row.
Along with the creation of the zone in the East China Sea, the defence ministry released a set of aircraft identification rules that must be followed by all planes entering the area, under penalty of intervention by the military.
Aircraft are expected to provide their flight plan, clearly mark their nationality, and maintain two-way radio communication allowing them to "respond in a timely and accurate manner to the identification inquiries" from Chinese authorities.
The outline of the new zone, which is shown on the ministry website and a state media Twitter account, covers a wide area of the East China Sea between South Korea and Taiwan that includes the Tokyo-controlled islands known as the Senkaku to Japan and Diaoyou to China.
"China's armed forces will adopt defensive emergency measures to respond to aircraft that do not co-operate in the identification or refuse to follow the instructions," according to the ministry.
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The zone became operational as of 10am on Saturday (1300 AEDT).
Four Chinese coastguard boats briefly entered Senkaku waters on Friday, following multiple incursions at the end of October and start of November which revived tensions between Beijing and Tokyo.
Japanese Defence Minister Itsunori Onodera said in late October that the repeated incursions were a threat to peace and fell in a "grey zone (between) peacetime and an emergency situation".
A few days earlier, the Chinese defence minister warned Japan that any bid to shoot down its drones would constitute "an act of war".
The move came after a report said Japan had drafted plans to shoot down foreign drones that encroach on its airspace if warnings to leave are ignored.
Sino-Japanese relations have remained at a low-ebb for more than a year as a result of the dispute, which was revived when Japan nationalised three of the archipelago's five islands in September 2012.
Since that time, China has sent regular coast guard patrols to the islands, which are 200 kilometres northeast of Taiwan and 400 kilometres west of Japan's Okinawa.
