Tension between Japan and China has escalated over the new Japanese leader's suggestion Tokyo could intervene militarily if Beijing attacks Taiwan.

From China’s point of view, the Japanese Prime Minister’s remarks on Taiwan test a red line - a trigger that sets this dispute apart from past flare-ups, analysts say.

Takaichi, a hardline conservative who was approved by parliament as Japan's first female prime minister last week, is a regular visitor to Tokyo's Yasukuni shrine, which honours Japan's war dead, including soldiers and officials convicted of war crimes by an international tribunal.

Beijing is flexing its military and economic might to show its displeasure with the Japanese leader’s comments about defending Taiwan. But its aggressive approach risks backfiring.

The diplomatic row over comments on Taiwan has evolved from a war of words to Beijing advising its citizens against travelling and studying abroad in Japan.

A diplomatic feud with China sparked by Japanese Prime Minister Sanae Takaichi’s comments about Taiwan has underscored the fragility of ties between the