Six Chinese surveillance ships briefly entered waters near disputed islands claimed by Tokyo and Beijing on Friday, raising tensions between Asia’s two biggest economies to their highest level since 2010.Japan protested to China and urged that the situation not be allowed to escalate - an outcome neither side would welcome given the two countries’ tight economic links.Diplomats say Tokyo and Beijing would prefer to keep the row from spiralling out of control, but with China facing a once-in-a-decade leadership change, an election looming in Japan and mutual mistrust deep, managing the feud could be difficult."The dangers of miscalculation are real,” said Brad Glosserman, executive director at Honolulu’s Pacific Forum CSIS.China’s foreign ministry said that the ships entered the disputed waters to conduct maritime surveillance and that for the first time China was carrying out a mission of "law enforcement over its maritime rights”.The Japanese coast guard said it ordered the Chinese ships to leave the area. By afternoon, all had left the area without any use of force, a coast guard official said.The islands, known as Senkaku in Japanese and Diaoyu in Chinese, are near potentially huge maritime gas and oil fields."We lodged a strong protest and also we made a strong case that the Chinese side should leave from the territorial waters around the Senkaku islands,” Japanese Foreign Minister Koichiro Gemba told a news conference in Sydney after talks with Australia’s foreign and defence ministers.