Prime Minister Fumio Kishida declined to meet with former Chinese Ambassador to Japan Kong Xuanyou before his departure in late February, multiple sources have confirmed, in an unusual move that indicates the degree of strain on bilateral relations.

Several of Kong's predecessors met Japanese premiers to bid farewell, but Kishida broke the custom in light of worsening public sentiment amid Chinese vessels' repeated entry into waters near the Tokyo-controlled Senkaku Islands and the past flights of suspected Chinese spy balloons over Japan, the sources said.

Japanese Prime Minister Fumio Kishida (L) and former Chinese Ambassador to Japan Kong Xuanyou. (Kyodo)

The request for an in-person farewell by Kong, who was succeeded by former Chinese Assistant Foreign Minister Wu Jianghao in March, was made to the Japanese government around January but Tokyo declined, citing a "schedule conflict" for Kishida, they said.

Foreign Minister Yoshimasa Hayashi met with Kong instead, but this meeting was not made public by his ministry, the sources added.

A government source said the rejection of Kong's request "did not cause any problem in terms of diplomatic protocol" as prime ministers are ranked above ambassadors.

Japan thought it is necessary to "take a reciprocal approach" after a meeting between former Japanese Ambassador to China Yutaka Yokoi and Chinese President Xi Jinping did not materialize before the envoy's departure in 2020, the source said.

With the two Asian neighbors commemorating the 45th anniversary this year of the 1978 bilateral Peace and Friendship Treaty, Tokyo and Beijing have been trying to stabilize relations by exploring a visit by Hayashi to China.

However, bilateral relations remain precarious amid an increasing rivalry between China and the United States -- Japan's primary security ally -- as well as Beijing's military pressure on Taiwan and its close ties with Russia amid Moscow's invasion of Ukraine.

Among five Chinese ambassadors to Japan who served since 2001, only one other was unable to meet the country's prime minister before his return to China.

In September 2007, Wang Yi, now China's top diplomat, departed without meeting then Prime Minister Shinzo Abe, who abruptly announced his intention to step down that month due to deteriorating health.

In April 2019, Abe hosted a luncheon at his official residence for Kong's immediate predecessor Cheng Yonghua and met with Kong at the prime minister's office upon his arrival in Japan in June that year.

Abe returned to power in 2012 and became Japan's longest-serving leader before he was assassinated last year during an election campaign speech.

China claims the Japan-controlled Senkaku Islands in the East China Sea, calling them Diaoyu, and repeatedly sends its vessels into waters near the islets.