"China always advocates that the disputes on this issue between China and Japan should be resolved through consultation," foreign ministry spokesman Kong Quan told a regular briefing.

"Both sides should refrain from any unilateral action."

The Japanese plan calls for the dispatch of 55,000 troops as well as warplanes, destroyers and submarines from Japan's main islands in the event of an attack on Okinawa and other remote islands, Kyodo news agency said earlier.

The islands include the Senkakus, known in Chinese as the Diaoyu islands, which both countries claim as their own.

"China takes this seriously and has reaffirmed on many occasions that Diaoyu island and its related islands have been part of Chinese territory since ancient times," said Kong.

In November Japan made public its new defense guidelines which for the first time explicitly point to China as a potential threat, along with North Korea.