Photo/Illutration The Great Hall of The People in Beijing on March 4 (Sotaro Hata)

BEIJING—A Japanese employee of Astellas Pharma Inc. who has been detained here on suspicion of espionage since March of last year was indicted in mid-August, a source close to Japan-China relations said on Aug. 21.

The decision is expected to further prolong his detention in China, although the specific nature of the charge against him remains unclear, the source said.

Officials from the Japanese Embassy in Beijing have met with the employee once a month during his detention and confirmed that he has no health problems, the source said.

A spokesperson for Astellas, a Japanese pharmaceutical company, declined to comment beyond confirming that the employee was indicted, saying that the case is pending trial.

Japan has pressed China to release the man, but his detention is expected to continue due to court proceedings following the indictment. The issue will likely remain a thorn in the side of Japan-China relations.

The Japanese Embassy said it will continue to demand an early release of the employee.

A revised anti-espionage law went into effect in July last year, deepening anxiety among foreign businesspeople in China.

Experts have pointed out uncertainties about what China may deem as espionage, saying that the “spying activities” the country is cracking down on are not clearly defined.

If an espionage charge is established by a court, the accused faces an imprisonment term ranging from three years to indefinitely.

The death penalty is possible for crimes concerning national security, including espionage, if the harm caused to the state is considered particularly grave.