TOKYO - China's declaration of an air defence identification zone that includes disputed islands is "profoundly dangerous", Japan's prime minister said Monday, as South Korea weighed into the war of words against Beijing.
Shinzo Abe's warning comes after Washington said it would stand by Japan in the event of any military clash over the Senkaku Islands, which Beijing claims as the Diaoyus.
"I am strongly concerned as it is a profoundly dangerous act that may cause unintended consequences," Abe told parliament.
"Japan will ask China to restrain itself while we continue cooperating with the international community," he said.
The comments are the first from the premier on the issue since Beijing on Saturday announced it would require all aircraft flying over an area of the East China Sea to obey its orders.
US Secretary of State John Kerry declared Washington "deeply concerned", saying the move raised "risks of an incident".
"This unilateral action constitutes an attempt to change the status quo in the East China Sea," Kerry said.
In announcing the new rules, a Chinese defence ministry spokesman said they would safeguard territorial sovereignty and maintain "flight order".
Aircraft are now 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 identification inquiries from Chinese authorities, the defence ministry said.
The announcement of the area, which also includes waters claimed by Taipei and Seoul, provoked ire in both cities.
Part of the zone overlaps South Korea's own air defence zone and incorporates a disputed, submerged, South Korean-controlled rock - known as Ieodo - that has long been a source of diplomatic tension with Beijing.
"I'd like to say once again that we have unchanging territorial control over Ieodo," defence ministry spokesman Kim Min-Seok said Monday.
In Taipei, which also claims the Senkakus, the government pledged to "defend its sovereignty over the archipelago, protect the rights of Taiwan fishermen in surrounding waters, and maintain patrols to safeguard fishing activities".
Japan's foreign ministry said it would not respect the Chinese demarcation, which it said had "no validity whatsoever in Japan".