AKIPRESS.COM - Japan warned China on Tuesday that ties were deteriorating over disputed East China Sea islets, and China's envoy in Tokyo reiterated Beijing's stance that the specks of land were its territory and called for talks to resolve the dispute, Reuters reports.

The diplomatic tussle comes amid simmering tension as China builds on outposts in the contested South China Sea, including what appear to be reinforced aircraft hangars, according to new satellite images.

Ties between Asia's two largest economies have been strained in recent days since Japan saw a growing number of Chinese coastguard and other government ships sailing near the East China Sea islets, called the Senkaku in Japan and Diaoyu in China.

The flurry of Chinese incursions into the waters follows a period of sustained pressure on China over its activities in the South China Sea, and China's criticism of what it sees as Japanese interference in that dispute.

Japanese Foreign Minister Fumio Kishida called in Chinese ambassador Cheng Yonghua for the second time since Friday and told him China was trying to change the status quo unilaterally, the Japanese foreign ministry said.

Kishida told Cheng the environment surrounding Sino-Japanese ties was "deteriorating markedly", the ministry said.

The Chinese diplomat said after the meeting that he had told Kishida the islands, which are controlled by Japan, were an integral part of China's territory and the dispute should be resolved through dialogue.

"I told him ... it is natural that Chinese ships conduct activity in the waters," Cheng told reporters.

Dozens of Chinese vessels sailed near the islands on the weekend raising alarm in Japan. Cheng was called in by Japanese Vice Foreign Minister Shinsuke Sugiyama last Friday over the incursions into what Japan see as its territorial waters.

The United States, its Southeast Asian allies and Japan have questioned Chinese land reclamation on contested islands in the South China Sea, particularly since an international court rejected China's historic claims to most of that sea last month.