China warned Japan on Thursday not to refer to Taiwan in its long-term security policy guideline slated to be updated by the end of the year, saying Tokyo should "refrain from interfering in China's internal affairs."

Tokyo is planning to mention in the revised National Security Strategy that "no unilateral change of the status quo by force will be tolerated" over Taiwan, according to a Japanese government source, with China recently stepping up military provocation against the self-ruled democratic island.

Tan Kefei, spokesman of China's Defense Ministry, told a press conference Thursday that Japan has "played up the so-called military threat" of Beijing, which is based on "an ulterior motive and irresponsible." He urged Tokyo to be "cautious in its words and deeds" in the security field.

The spokesman also expressed China's "firm opposition" to a bill deliberated at U.S. Congress aimed at significantly enhancing American support to Taiwan, including through billions of dollars in security assistance, amid Beijing's increasing pressure on the island.

"We urge the U.S. side to stop playing with fire on the Taiwan issue," Tan said.

China-U.S. relations have sharply deteriorated since House of Representatives Speaker Nancy Pelosi visited Taiwan in August, with Beijing conducting large-scale military drills near the island following her trip.

Asked about U.S. Defense Secretary Lloyd Austin's remarks that Washington is trying to reopen the military communication channel with Beijing, the spokesman said the United States should "earnestly respect China's interests and major concerns, and dispel the negative factors hindering the relations between the two militaries."

Meanwhile, Chinese President Xi Jinping said in a message sent Wednesday to the National Committee on U.S.-China Relations that Beijing "stands ready to work with the United States to find the right way to get along with each other in the new era on the basis of mutual respect, peaceful coexistence and win-win cooperation."

The message to the U.S. nonprofit organization, reported by the official Xinhua News Agency, could be a gesture to seek an improvement in bilateral ties.

Xi also said "closer communication and cooperation between China and the United States will help bring greater stability and certainty to the world, and promote world peace and development."

U.S. President Joe Biden has expressed eagerness to meet Xi on the sidelines of the summit of the Group of 20 major economies scheduled for November in Indonesia.