Japan will carry out a tabletop exercise next week to simulate its response in the event of a military clash between China and Taiwan, Japanese media said.

The Self-Defence Forces will conduct drills from Monday through Friday with the US military participating as an observer, a Japanese government source told Kyodo News.

The exercises, which do not involve actual troop deployments, assume that the US and Japan are responding to a military conflict, Kyodo said in its Thursday report.

A Japanese defence ministry spokesman declined to comment.

China's foreign ministry said Japan should keep out of what it called an "internal affair".

"I think this reflects that some people in Japan have a certain mentality that the last thing they want is a stable world," ministry spokeswoman Hua Chunying told a regular press briefing in Beijing on Friday.

"I want to emphasise that the Taiwan issue is an internal affair of China, and we hope that Japan will be very cautious with its words and actions...and not do anything that would undermine regional peace and stability."

Relations between China and self-ruling island Taiwan, which Beijing views as a renegade province, have become increasingly strained since Donald Trump's November election as US president.

China was incensed by a protocol-smashing phone call between the billionaire and Taiwan's leader Tsai Ing-wen.

It was further angered by Trump's suggestion that the "one China" policy could be negotiable and demanded Washington ban Taipei's delegation from the inauguration.

Next week's drills will test Japan's military after a new law expanded its powers beyond strict self-defense -- a condition of a pacifist postwar constitution.

The legislation, which took effect in March, technically allows Japanese troops to engage in combat overseas if Japan's security is threatened.