China lodged representations on Friday over a Japan Self-Defense Force vessel entering the Taiwan Strait, urging Tokyo to stop "walking on the edge".

Japanese Prime Minister Sanae Takaichi has made erroneous remarks on the Taiwan question which have already seriously undermined China-Japan relations, Foreign Ministry spokesman Guo Jiakun told a daily news conference where he expressed firm opposition to the latest Japanese move.

By dispatching a Self-Defense Force vessel into the Taiwan Strait to flex muscle and deliberately stir up provocation, Japan has compounded its mistake, Guo said.

He added that the Chinese military has handled the incident in accordance with laws and regulations.

Guo said the dispatch of the vessel once again exposes the dangerous attempts of certain people in Japan to intervene militarily in the Taiwan Strait and undermine cross-Strait peace and stability.

The Taiwan question is fundamental to China's sovereignty and territorial integrity, and the political foundation of China-Japan relations, he said, stressing that it is a red line that must not be crossed.

Guo added that China urges Japan to reflect on its actions, correct its mistakes, speak and act with extra prudence, and stop going further down the wrong path.