Shen Jinke, spokesperson of the People's Liberation Air Force (PLAF), said "two large scout aircraft carried out the patrol mission, with early warning aircraft and fighters providing support". (Agencies)
"The patrol is in line with international common practices and the normal flight of international flights will not be affected," Shen said.
It was not clear whether the air patrols flew over the chain of disputed islands called Diaoyu by China and Senkakus by Japan but the new "East China Sea Air Defence Identification Zone" covers the area, state-run news agency reported.
This was perhaps the first time China has conducted air patrols challenging the Japanese air monopoly over the islands, which controlled them till last year.
Chinese ships have been conducting patrols near the islands since late last year.
Earlier, the Chinese Defence Ministry announced that aircraft entering the air defence zone will have to inform China or face "emergency defensive measures". It said the move will not affect international flights over the zone.
Under new Chinese rules, aircraft entering the zone will have to report their flight plans to the Chinese Foreign Ministry or the Civil Aviation Administration of China.
Shen said the Chinese armed forces are capable of effective control over the zone and will take measures to deal with air threats to protect the country's airspace.
Defence Ministry spokesperson Yang Yujun said China will take timely measures to deal with air threats and unidentified flying objects from the sea, and hoped all relevant sides positively cooperate and jointly maintain flying safety.
"It is a necessary measure in China's exercise of self-defence rights. It has no particular target and will not affect the freedom of flight in relevant airspace," he said.
Asked on what grounds China established the zone, he said, "Since the 1950s, over 20 countries, including some big powers and China's neighbouring countries, have set up air defence identification zones."
If enforced strictly the new Chinese law could spark off major military tensions with Japan, which has been administering the group of islets believed to be rich with minerals and hydro carbons.
China stepped up its protests over Japanese control from September last year after Tokyo bought the islets from a private Japanese party. China said this amounted to nationalization of the islands and pressed its fleet of war ships to patrol aggressively with that of Japanese patrols.
Currently the coast guard ships of both countries aggressively patrol the waters of the islands every day, warning each other while blaring their sovereignty claims over their communication systems.
Observers say that the new zone will take the dispute to a new level, creating fresh tensions as Japan too is aggressively gearing up to militarily defend its claims of sovereignty over the islands. The move came as the two countries tried to defuse tensions through backdoor diplomacy to protect their USD 345 billion bilateral trade.
Shen Jinke, spokesperson of the People's Liberation Air Force (PLAF), said "two large scout aircraft carried out the patrol mission, with early warning aircraft and fighters providing support".