The Chinese embassy in Japan said on Sunday that it "resolutely opposed" Japanese Foreign Minister Yoko Kamikawa's statement congratulating Taiwan's new president-elect Lai Ching-te.

In a statement published on the Japanese foreign ministry's website on Saturday, after the results of the Taiwan presidential election were announced, Kamikawa congratulated Lai on his victory, calling the self-ruled island claimed by Beijing "an extremely crucial partner and an important friend."

In response, the Chinese embassy in Japan, without mentioning Lai or acknowledging his victory, described Kamikawa's comments as "a serious interference in China's internal affairs", according to a statement published on Sunday on the embassy's official WeChat account.

"We express strong dissatisfaction and resolute opposition to this, and have lodged solemn representations with the Japanese side," the embassy said.

Japan, like most countries, does not have official diplomatic relations with Taiwan, a precondition for establishing diplomatic ties with China.

But Japan's alliance with the United States, Taiwan's most important backer, and its proximity to the island, along with recent tensions in its ties with China, have prompted Tokyo to pursue closer ties with Taipei.

"The Government of Japan will work toward further deepening cooperation and exchanges between Japan and Taiwan," Kamikawa said in her statement.

The Chinese embassy also said that Japan should refrain from sending any "wrong signals" to "Taiwan independence" forces, a label Beijing uses to describe Lai and his political party, the Democratic Progressive Party (DPP), which champions Taiwan's separate identity and rejects China's territorial claims.

Lai said he would maintain the status quo in relations across the Taiwan Strait, but that he was "determined to safeguard Taiwan from threats and intimidation from China".