TOKYO (Reuters) - Japanese Prime Minister Shinzo Abe criticised Beijing for trying to "change the status quo" with force in maritime disputes but said China was a vital economic partner, as a series of visits suggested a possible thaw in ties between the Asian rivals.
Sino-Japanese ties have been strained by a territorial row over tiny disputed isles in the East China Sea and perceptions in Beijing that Mr Abe wants to rewrite Japan's wartime history and tone down past apologies.
"China's growth is a chance for Japan, and for the world as well. China is Japan's largest trading partner and we are in inseparable relations economically," Mr Abe said at a symposium. "On the other hand, it is true that China is challenging the status quo with force in the East China Sea and South China Sea," he said, referring to Beijing's territorial rows with several South-east Asian countries as well.
"It is necessary for not only Japan but many other countries to prompt China to grow peacefully as a responsible country."
China's People's Liberation Army is building submarines, surface ships and anti-ship ballistic missiles, and has tested emerging technology aimed at destroying missiles in mid-air. The military modernisation has also been accompanied by a more assertive posture in its territorial disputes.
Mr Abe, who returned to office in December 2012, has yet to hold a summit with Chinese President Xi Jinping due to the tensions in ties between Asia's two biggest economies.
Relations, often frayed by the legacy of Japan's wartime aggression and occupation of parts of China, are also strained by the row over the East China Sea isles, known as the Senkakus in Japan and the Diaoyus in China.
But a series of visits and planned visits between the two countries has prompted speculation over a possible shift, as has an article by two academics that appeared in the Washington Post showing the frequency of Chinese maritime patrols in waters that Japan considers its own had declined over the past six months, possibly signalling Beijing's desire to cool things down.
An April 24 to 26 visit to Beijing by Tokyo Governor Yoichi Masuzoe, elected to his post with the backing of Mr Abe's Liberal Democratic Party (LDP), is grabbing the most attention.
"If two important cities from the two countries can start to mend the relationship, of course that will have a positive impact on the whole China-Japan relationship," said Mr Jin Canrong, associate dean of the School of International Studies at Renmin University in Beijing. "This shows that both sides want to open a channel for dialogue outside of the central government."
Mr Jin said the decrease in Chinese maritime patrols in disputed waters could signal a desire to soothe tensions. A Japanese expert agreed, but said the publication of the article noting the change could have a negative impact. "They will de-escalate when no one notices," said Mr Narushige Michishita, a professor at the National Graduate Institute for Policy Studies in Tokyo.
"But if people notice, they might have to go back, especially the Chinese side."
Among other moves that have caught attention are Mr Abe's reported meeting this month with the son of the late Chinese Communist Party General Secretary Hu Yaobang and a meeting on Tuesday between Chinese Vice-Premier Wang Yang and a Japanese trade delegation headed by former Chief Cabinet Secretary Yohei Kono, in whose name a 1995 apology over women, mostly Asian, forced to work in Japan's wartime military brothels, was issued.
Mr Liu Jiangyong, an expert on Sino-Japan relations at Beijing's Tsinghua University, cautioned against reading too much into recent moves. "There has been no recent material change (in the Sino-Japan relationship)," he said.