The Ministry of National Defense has rejected the Japanese media's latest "hype" over the alleged naval "radar lock-on" incident and warned of a hidden agenda behind Tokyo's recent reports.

In the latest chapter of the radar "drama", the Tokyo-based Kyodo News Agency released an article on Sunday quoting unnamed Chinese officials who reportedly admitted to "locking radar on Japanese ships".

Beijing previously dismissed the allegation as groundless, while the ministry denied the Kyodo report, reiterating on Monday that "the facts are clear".

Sino-Japanese ties have been strained by the deadlocked Diaoyu Islands row since September.

In early February, Japanese Defense Minister Itsunori Onodera heightened tension by claiming that a Chinese navy vessel had "locked its fire-control radar" on a Japanese destroyer in the East China Sea in late January.

The accusations have tarnished the image of China's military and misled international public opinion because of Japan's "ulterior motives", the ministry said.

Japanese warships and aircraft have for a long time closely followed, monitored and disturbed Chinese naval ships and aircraft, according to the ministry.

Huo Jiangang, an expert on Japanese studies at the China Institutes of Contemporary International Relations, said Tokyo has resorted to a series of groundless allegations, especially the "radar" incident, to accuse China of being responsible for "escalating the tension" and "violating international norms".

"Tokyo is trying to contain China by language and publicity approaches that have a worldwide reach," Huo warned.

Japan should maintain China-Japan ties with practical action and deeply reflect on the practice instead of making irresponsible comments, the ministry said.

Tension between the two largest Asian economies continued on Monday, as China marine surveillance vessels continued regular patrols in the waters off the islands on Monday, the Japanese coast guard said.