Beijing has condemned Japanese Prime Minister Shinzo Abe for "maliciously slandering" its air defence zone in an escalating war of words.
Abe told a news conference on Saturday that China's recent announcement of the air defence identification zone over the disputed Diaoyu, or Senkaku, islands in the East China Sea is "unjustly violating the freedom of aviation over the high seas".
He demanded that Beijing rescind it.
But Chinese Foreign Ministry spokesman Hong Lei defended the zone, which has triggered protests from Japan, South Korea and the United States.
"We express strong dissatisfaction with Japan's leader using an international occasion to maliciously slander China," Hong said in a statement on the ministry website.
"The Diaoyus are an inherent territory of China. Japan's seizure and occupation of the islands are illegal and invalid," Hong said. He added that the zone is in line with international laws and practices and does not affect aviation freedom.