China on Thursday urged Japan to demonstrate its commitment to the one-China principle through practical actions and refrain from supporting "Taiwan independence" separatist forces in any form.

Chinese Foreign Ministry spokesperson Wang Wenbin made the remarks at a regular press briefing when asked about Japan's recent negative moves on the Taiwan question.

Wang said Japan has frequently made negative moves on the Taiwan question in recent years and that China has, in response, made solemn representations, stating its position to the Japanese side.

The Taiwan question bears on the political foundation of China-Japan relations and is the number one red line that must not be crossed, the spokesperson said.

He urged Japan to abide by the principles and spirit of the four political documents between China and Japan and warned that anyone who insists on interfering in China's internal affairs and obstructing its reunification will surely pay a heavy price.

(Cover: A view of Chinese Foreign Ministry. /CFP)