SHANGHAI, Muharram 20, 1435, Nov 23, 2013, SPA -- China on Saturday bolstered its claim to islands that Japan says it owns, warning that it would take "defensive emergency measures" against aircraft that failed to identify themselves properly in airspace over them, Reuters reported. Ties between the Asian powers have been strained for months by the dispute over the islands in the East China Sea, called the Diaoyu by China and the Senkaku by Japan, which are believed to be surrounded by energy-rich seabed. China's government-run Xinhua news agency published a map and coordinates for the newly-established "East China Sea Air Defence Identification Zone", which covers most of that sea including the disputed islands. Japan on Saturday afternoon scrambled fighter jets against two Chinese reconnaissance planes over the East China Sea, the Japanese Defence Ministry said. A ministry spokesman declined to comment on whether there was any connection between the Chinese patrol activity and the two reconnaissance planes. He said one of the aircraft, a TU-154, came as close as 40 km (25 miles) to what Japan considers its airspace above the disputed islands. A Japanese Foreign Ministry spokesman said Japan had lodged a strong protest with China's embassy in Tokyo and reiterated its position that the islands belonged to Japan and China's action was not acceptable. -- SPA 18:44 LOCAL TIME 15:44 GMT www.spa.gov.sa/1171115