Japanese and South Korean military aircraft flew through disputed air space over the East China Sea without informing China, Chinese officials said yesterday.
The flights were a challenge to the Chinese declaration of an exclusionary air defence zone that has fuelled regional tensions and sparked concerns of an unintended clash.
China demanded that planes flying through the zone identify themselves. But on Tuesday Tokyo's close ally, Washington, defied China and flew two unarmed B-52 bombers over the islands without informing Beijing.
Tensions have ratcheted up since Beijing's weekend announcement of the zone, which includes the skies over islands - known as the Senkaku in Japan and the Diaoyu in China - that are at the heart of a feud between Japan and China.
Japan and the US have criticised China's demand, which some experts said was aimed not only at chipping away at Tokyo's control of the islands but also at challenging US military dominance in the region.
The US does not take a position on who has sovereignty over the islands but recognises Tokyo's administrative control and has assured Japan that the US-Japan security pact covers them.
The developments are expected to dominate US Vice-President Joe Biden's visit to Japan, China and South Korea next week.
China yesterday rejected South Korea's demand for the repeal of the declaration of the zone but appeared to soften its insistence that airlines tell its military authorities of plans to overfly the area.
Japan's two biggest airlines have already begun defying the order.
"The identification zone is not aimed at normal international flights. We hope relevant countries' airlines can cooperate," China's foreign ministry said.
Japan said naval vessels and patrol planes have been operating in the zone and would not stop.
"We are not going to change this out of consideration for China."
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