TOKYO >> Japan’s Foreign Minister Yoshimasa Hayashi protested in a meeting Sunday with his Chinese counterpart the detention of a Japanese national in Beijing and raised “strong concern” about China’s escalating military activity near Taiwan and around Japan.

Hayashi is on a two-day visit to China, becoming Japan’s first diplomat to make the trip in more than three years as frictions grow between the countries. He also met Chinese Premier Li Qiang and top diplomat Wang Yi later Sunday.

During his talks with Chinese Foreign Minister Qin Gang, Hayashi demanded an early release of an employee of the Japanese pharmaceutical company Astellas Pharma, who was detained in Beijing last month over what the Chinese Foreign Ministry described as spying allegations. Neither side has offered further details about the man nor the allegations against him.

Hayashi told reporters he raised “serious concern” about China’s increasingly assertive activity in the East and South China seas, and stressed the importance of peace and stability in the Taiwan Strait.

He said he also expressed grave concern about Beijing’s increased joint military activity with Russia around Japan while Moscow wages war against Ukraine, and urged China to act responsibly for global peace.

Hayashi said he told Qin while there is a possibility of improving cooperation in economic, cultural and people exchanges, the two countries also face “many problems and serious concerns” and that “Japan-China relations are currently at an extremely important phase.”

The two ministers agreed to work together in achieving “a constructive and stable relationship” as agreed between their leaders in November, Hayashi said.

The sides agreed to improve communication in regional security, and welcomed the establishment of a defense hotline last week and the resumption of defense talks, Hayashi said.

Hayashi said that he and Premier Li shared the importance of their bilateral economic ties, and that it was crucial that Japanese nationals and companies feel safe to operate in China.

That was the concern raised by representatives of Japanese companies during their meeting Saturday with Hayashi. They also sought transparent, predictable and fair business environment in China, said Yukiko Okano, deputy press secretary for the Japanese Foreign Ministry.

Separately, Hayashi told Wang that China’s assertive activity in the East China Sea and the recent detention are “a stumbling block for promoting economic and people-to-people exchanges.”

Despite close economic and business ties between the two Asian powers, Tokyo and Beijing have been increasingly at odds in recent years as Japan considers China’s growing influence in the region a threat to its security and economy.

Qin meanwhile warned against Japanese involvement in issues related to Taiwan, the self-ruled island that China claims as its own, saying Tokyo should not interfere and “undermine China’s sovereignty in any way,” according to a statement from China’s Ministry of Foreign Affairs.

Using strong language, Qin said “the Taiwan issue is at the core of China’s core interests and concerns the political foundation of China-Japan relations.”

Japan does not formally recognize Taiwan, but has strong unofficial ties with the island. It has been making statements of concern about regional stability in the Taiwan Strait and sent several prominent parliamentary delegations to Taipei.

Japan is increasingly worried about a potential Chinese invasion of Taiwan because of its proximity to southwestern Japanese islands as well as disputed East China Sea islands, which are claimed by both Tokyo and Beijing, and has bolstered its defenses recent years.

The Japan coast guard said in a statement over the weekend that three Chinese coast guard ships had entered the Japanese-controlled waters around Senkaku Islands, which Beijing calls the Diaoyu. A Japanese patrol ship repeatedly demanded they leave while protecting two Japanese fishing boats, the coast guard said.

Qin criticized Japan over its new export controls of semi-conductor manufacturing equipment that require companies to get government permission. The U.S. has imposed similar measures and Japan had acknowledged consulting with Washington on its own regulation.

“The U.S. once used bullying tactics to brutally suppress Japan’s semiconductor industry, and now it is repeating the same old tricks against China,” Qin said, urging Japan not to be America’s pawn. “One should not do unto others what one would not have done unto oneself.”

Hayashi said the measure is not targeting any specific country. But it was seen as part of a U.S.-led agreement to make sure advanced semi-conductor manufacturing stays out of the reach of the Chinese industry.

The last Japanese foreign minister to visit China was Hayashi’s predecessor, Toshimitsu Motegi, in 2019, just before China imposed rigorous pandemic border controls and other measures.