China is to carry out a geographical survey of islands in the East China Sea at the centre of a bitter dispute with Japan, state media said on Tuesday. The survey of the Diaoyu Islands – known as Senkakus in Japan, which controls them – was part of a programme to map China’s “territorial islands and reefs”, the Xinhua news agency said, citing a state geographical agency. The maritime dispute, which has simmered off and on for years, intensified last year when the Japanese government nationalised islands in the small chain it did not already own, triggering anger and demonstrations in China. The protests were allowed to take place by the Communist authorities in Beijing, who use nationalism to bolster their claims to legitimacy, particularly regarding Japan, which occupied parts of China in the 20th century. The mapping exercise was part of China’s efforts to “safeguard its maritime rights and interests”, Xinhua said, without saying when it would take place or making clear whether it would involve activities on land, as opposed to sea-based surveying. It quoted Zhang Huifeng, an official with China’s National Administration of Surveying, Mapping and Geoinformation, acknowledging that there could be “difficulties”. “There are some difficulties in landing on some islands to survey, and in surveying and mapping the surrounding sea area of the islands, because some countries infringed and occupied these islands of China,” he said. Both Tokyo and Beijing have scrambled fighter jets to the area in recent weeks in a further escalation of the row, though no actual clashes have taken place. China’s armed forces have been instructed to raise their fighting ability this year and “should focus closely on the objective of being able to fight and win a battle”, state media said. Japanese public broadcaster NHK reported on Monday that Japan will deploy two more patrol ships to boost its defence of the islands and has conducted its first drill simulating the recapture of an isle seized by enemy forces. Xinhua said that the survey was part of a programme begun in 2009 and by the end of last year, China had completed the identification and “precise positioning” of approximately 6,400 islands. In September China announced the “base points and baselines of the territorial waters of the Diaoyu Islands”, filing details with the United Nations as part of the diplomatic sparring over the issue. Within days China’s State Oceanic Administration released geographic information about the islands in what Xinhua called a “new move to affirm China’s sovereignty”. The data included “the exact longitude and latitude of Diaoyu Island and 70 of its affiliated islets”, along with “location maps, three-dimension effect graphs and sketch maps for the Diaoyu Islands”, Xinhua added. Last month Beijing also submitted to the UN information on the outer limits of its continental shelf in a bid to bolster its claim to the islands. China also has disputes with several Southeast Asian countries over islands and reefs in the South China Sea. Japan, meanwhile, has a dispute with South Korea over small islets in waters about halfway between their countries. Tokyo also has a long-running dispute with Russia over northern islands seized by the Soviet Union at the end of the second world war.