Japan's plan to deploy offensive weapons on islands near China's Taiwan region is "extremely dangerous", Foreign Ministry spokeswoman Mao Ning warned on Monday.

Mao made the remarks in response to reports that Japanese Defense Minister Shinjiro Koizumi had visited an island near Taiwan where he talked about Japan's plan to deploy medium-range surface-to-air missiles on the island.

The deployment deliberately stokes regional tension and military confrontation, Mao said.

"Given Japanese Prime Minister Sanae Takaichi's erroneous remarks on Taiwan, this move is extremely dangerous," she said.

"The neighboring countries and the international community should be on high alert."

The Potsdam Proclamation, which followed Japan's defeat in World War II, explicitly stipulates that Japan should not be permitted to re-arm for war, Mao said, adding that Japan's pacifist constitution also established the country's exclusively defense-oriented policy.

"But alarmingly, in recent years, Japan has drastically readjusted its defense policies, increased its defense budget year-by-year, loosened restrictions on weapons exports, and sought to develop offensive weapons and abandon the Three Non-Nuclear Principles," Mao said.

"Japanese right-wing provocateurs are doing all they can to break free from the pacifist constitution, and going further down the wrong path of military buildup, leading Japan and the region to disasters," she said.

Noting that this year marks the 80th anniversary of victory in the Chinese People's War of Resistance Against Japanese Aggression (1931-45) and Taiwan's restoration to China, Mao said Beijing "will never allow Japanese right-wing provocateurs to turn back the wheels of history" or allow "external forces to lay their hands on China's Taiwan region".

"China is determined and capable of defending its territory and sovereignty," she said.