Beijing has protested to Tokyo over Prime Minister Sanae Takaichi’s contact with a former senior Taiwanese politician on the sidelines of the Apec summit in South Korea, describing the action as “egregious”.

Takaichi posted photos of herself meeting Lin Hsin-i on social media on Friday and Saturday, referring to him as “senior adviser to the Presidential Office of Taiwan”.

In the comments she said she hoped the “practical cooperation between Japan and Taiwan will deepen”.

In a statement on Saturday, China’s foreign ministry said Takaichi deliberately met “personnel from the authorities of China’s Taiwan region … [and] hyped it on social media”.

“Those actions severely violated the one-China principle, the spirit of the four political documents between China and Japan, and basic norms of international relations, and sent a gravely wrong signal to the ‘Taiwan independence’ forces,” the statement said.

“Those actions are egregious in nature and impact. China expresses its firm opposition and has made serious demarches and protests to Japan.”