Beijing –

A court in China sentenced a Japanese businessman on Wednesday to three and a half years in prison for spying, Tokyo's ambassador in Beijing said.

The man, an employee of the Japanese pharmaceutical company Astellas Pharma, was detained in March 2023 and placed under formal arrest in October 2023.

He was "sentenced to three years and six months in prison for espionage activities," Kenji Kanasugi, Japan's ambassador to China, told Japanese media after the trial in Beijing. "It is extremely regrettable that such a guilty verdict was issued," he said.

The detained man has reportedly worked in China for two decades, and was previously a senior executive at a major Japanese business lobby in the country. He was planning to return to his home country before his sudden detention, according to Kyodo News.

Five Japanese nationals, including the Astellas official, are in custody or serving prison terms in China, according to national broadcaster NHK.

Tokyo had repeatedly called on Beijing to release them, and Wednesday's sentence deals a blow to ties long frayed over territorial disputes, Japan's colonial history and other flashpoints.

In light of the sentence, the Japanese Embassy in Beijing said in a statement that it had once again strongly urged the Chinese side to make arrangements for the early release of the Japanese national concerned in this case as well as others detained.

It also urged China "to ensure their legitimate rights and humane treatment during detention, and to improve the transparency of the judicial process."

The case has alarmed executives in China. Japanese companies are not the only organizations whose employees have been taken into custody. An executive and two former employees of WPP, one of the world’s biggest advertising companies, were arrested in China in 2023 in relation to a bribery investigation.

Chinese police also took into custody four Taiwanese employees at Hon Hai Precision Industry, Apple’s main assembly partner, last year.