China Thursday rejected remarks by US Senator John McCain describing the Diaoyu Islands as "Japan's territory," accusing him of complicating the regional situation.

"The Diaoyu Islands have been China's inherent territory. Any people's attempts to deny the fact are futile," Chinese foreign ministry spokesman Hong Lei told the Global Times in a statement. 

"We urge the relevant US Senator to stop making irresponsible remarks that would further complicate the issue and regional situation," he added.

At a press conference on Wednesday in Tokyo after his meeting with Japanese Defense Minister Itsunori Onodera, McCain expressed his support for Japan in its island row with China.

"The fact is the Chinese are violating fundamental rights that Japan has to the Senkakus (Diaoyu Islands). I think it would be a mistake to treat it any other way," he said, according to Japan's Kyodo News.

"To assume anything but the fact that the Senkakus are Japanese territory, I think, would be contradictory to the facts," he said.

McCain also said nations feeling increasingly threatened by China's maritime presence "need to act in closer coordination with each other" and present a united front to China.

Onodera expressed appreciation for a US Senate resolution in late July expressing concern about Chinese actions in the East China Sea and the South China Sea.

McCain's remarks represent a breach of Washington's stance that it does not take a position on the China-Japan island row, Su Hao, director of the Asia-Pacific Research Center at China Foreign Affairs University, told the Global Times.

He said that although McCain's comments do not represent the position of the US government, they would still have a negative impact on the bilateral relationship between China and the US as he is a very influential politician.

"China-US relations are witnessing positive signs, especially after Chinese defense minister Chang Wanquan's recent visit to the US," Su said, but noted McCain's remarks could damage efforts at developing diplomatic and security ties between Beijing and Washington.