Japan's ambassador to China called home Japan has called its ambassador to China back to Tokyo for discussions on a territorial dispute straining relations between East Asia's leading powers. The temporary return of ambassador Uichiro Niwa highlights growing tensions over the Japanese-controlled Senkaku, an uninhabited group of islands in the East China Sea that are also claimed by Beijing, which calls them the Diaoyu. Japan on Wednesday protested as "extremely serious" and "unacceptable" the entry of three Chinese state fisheries patrol vessels into territorial waters around the potentially resource-rich islands, which are also claimed by Taiwan. In an interview with the Financial Times in June, Mr Niwa warned that plans by the Tokyo municipal government to buy the Senkaku islands from their private Japanese owner could spark an "extremely grave crisis" between Japan and China. Government leaders quickly rebuked the ambassador for his remarks, which they dismissed as "personal opinions" that did not reflect the government position. Some Diet members from opposition groups and the ruling Democratic party called for Mr Niwa to be fired over the comments. However, Kyodo news agency quoted Koichiro Gemba, Japan's foreign minister, as saying the ambassador's return was temporary and was not intended to be seen as a protest to China. "[We] want to talk directly [with Mr Niwa] regarding the current situation in Japan-China relations and his analysis of it," Mr Gemba said in remarks broadcast on All-Nippon News Network. The Senkaku islands have long been considered one of East Asia's most dangerous flashpoints. A clash between a Chinese fishing boat and Japanese coastguard in the area in 2010 disrupted diplomatic and economic exchanges for months. Beijing and Taipei have both warned against plans announced this month by Japan's central government to buy the islands from their private Japanese owner. The central government currently rents the islands but bans landings on them to avoid upsetting China. The central government has proposed buying the islands itself, an approach officials see as the best way to maintain the status quo. The goal of such a purchase would be to "continue quiet and peaceful management of the Senkaku Islands and nearby seas," the government's top spokesman said last week. However, the proposed nationalisation of the islands has been greeted with bellicose language in Chinese official media. The Communist party-run Global Times newspaper, a popular forum for nationalist Chinese views, published an opinion piece by a senior military scholar saying the nation's new aircraft carrier should be named Diaoyu Islands and the military should use the disputed area for missile tests and live firing exercises. In an editorial, the newspaper has even argued that Beijing should consider questioning Japanese sovereignty over Okinawa - an island prefecture of 1.4m people - as a way of putting pressure on Tokyo. China should not be afraid of facing off against Japan in a "mutual undermining of territorial integrity," said the paper in comments that are sure to reinforce Japanese suspicions about Chinese intentions in the region. "Every time the Japan side take one step, we should take one-and-a-half or even two, to make them realise that provocation will have serious consequences," the Global Times said.