China has demarcated an "air-defence identification zone" over an area of the East China Sea, covering islands that are also claimed by Japan, according to BBC News.

China's Defence Ministry said aircraft entering the zone must obey its rules or face "emergency defensive measures".

The zone came into effect from 10:00 local time (02:00GMT) on Saturday, November 23.

The islands, known as Senkaku in Japan and Diaoyu in China, are a source of rising tension between the countries.

In its statement, the Defence Ministry said aircraft must report a flight plan, "maintain two-way radio communications", and "respond in a timely and accurate manner" to identification inquiries.

"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," said the statement.

A map posted on Twitter by state news agency Xinhua showed the zone covering a wide area of the East China Sea, including regions very close to South Korea and Japan.