Chinese President Xi Jinping has congratulated new Japanese Prime Minister Shigeru Ishiba, state media reported on Wednesday, the day after he took office in Tokyo.
Relations between the countries have worsened as China builds its military presence around disputed territories in the region, and as Japan boosts security ties with the United States and its allies.
Beijing last week reacted angrily and lodged a complaint with Tokyo after a Japanese warship sailed through the Taiwan Strait for the first time.
The United States and its allies are increasingly crossing through the 180-kilometre (112-mile) Taiwan Strait to reinforce its status as an international waterway, vexing China.
The Sazanami destroyer made the unprecedented passage on Wednesday, several Japanese media outlets said.
Beijing's foreign ministry spokesman Lin Jian said China was "highly vigilant about the political intentions of Japan's actions".
The countries have also clashed recently following the stabbing of a Japanese schoolboy in the southern Chinese city of Shenzhen.
- 'Steady development' -
But following Ishiba's victory, China has said it wants to improve ties with Japan, with Lin on Friday saying the "long-term, sound and steady development" of relations "serves the fundamental interests of the two peoples".
"It's the only appropriate choice," Lin said.
Ishiba, 67, says he intends to call a general election for October 27. He won a tight race on Friday to lead the Liberal Democratic Party, which has governed Japan almost continuously for decades.
The former defence minister outlined his policies at a news conference late on Tuesday, warning that "the security environment surrounding our country is the most severe since the end of World War II".
"With the Japan-US alliance as a foundation, we will expand the circle of friendly and like-minded countries, using diplomacy and defence to realise the peace of Japan and the region," he said.
AFP
Ishiba Shigeru becomes Prime Minister of Japan (Photo: Reuters)