Japanese Defense Minister Toshimi Kitazawa's call for stronger military ties with its allies to balance China's growing influence was described as "inappropriate" by a leading analyst.

In an interview with the Wall Street Journal on Friday, Kitazawa said "in order to maintain the right balance in our relationship with China, we need to also solidify the ties between Japan, the US and South Korea", adding that Japan was particularly concerned about China's increasing naval capabilities.

He also said Japan's relations with the United States were strengthened by the help its military provided in the aftermath of the March 11 earthquake and tsunami, the paper reported on Saturday.

"Our priority is to make our bilateral relationship with the US rock solid," he added.

Kitazawa's comments came after he thanked US forces for their help in the relief efforts.

His remarks on China were "very inappropriate" and could affect relations between Japan and China, said Zhou Yongsheng, a professor of Japan studies at China Foreign Affairs University.

"The Japan-US military alliance, shaped in the Cold War, should not be expanded or aimed at any third party."

China's military growth has never exceeded the necessary amount to maintain national security, Zhou added.

"The expansion of the Japan-US military alliance in the sensitive area of East Asia is harmful to regional peace and stability," Zhou noted.

Kitazawa's comments appear to show a change of attitude in the ruling Democratic Party of Japan, whose previous premier, Yukio Hatoyama, had promised a less subservient relationship with Washington.

Japan-US relations have improved somewhat since Prime Minister Naoto Kan assumed office, but a controversial base on Okinawa, which hosts more than half of the 47,000 US troops stationed in Japan, remains an irritant in ties between the security allies.

Japan's relations with China plunged to their lowest point in years last September after a fishing boat collided with Japanese coastguard ships near China's Diaoyu Islands in the East China Sea.