(Bloomberg) -- The Japanese government is seeking the release of an employee of Japanese drugmaker Astellas Pharma Inc. detained by Chinese authorities. 

The company is working with Japan’s foreign ministry to gather more information, a spokesman for Astellas said. Details on why the person was detained are still unknown. The government has requested a consular visit, Chief Cabinet Secretary Hirokazu Matsuno said in a briefing Monday. 

More than a dozen Japanese nationals have been detained in China since 2015, according to Kyodo News and other Japanese media. Eight people have returned to Japan, seven are still in China facing trial or serving time, while one has died, the Mainichi newspaper reported last month. Five of them have been found guilty by China of endangering national security, the paper said.

“Earlier this month, relevant Chinese authorities adopted compulsory measures in accordance with the criminal procedure law against a Japanese citizen for a case examination,” China Foreign Ministry spokeswoman Mao Ning said Monday at a regular press briefing in Beijing. “This Japanese citizen of engaging of espionage activities and violating the criminal law of the PRC and the counter-espionage law.”

NHK and other Japanese media reported over the weekend that the Astellas employee was in his 50s. He had worked for more than 20 years in China and was planning to return at the end of the month, FNN reported. He was detained in March for violating local law, according to the reports. 

In 2020, a Japanese man was released from detention in China after completing a five-year prison sentence. The man moved to North Korea in the 1960s, later defected and returned to Japan, according to Kyodo News. He was detained in 2015 close to the Chinese border with North Korea and sentenced to five years in 2018, it said. 

In 2021, a male employee of a trading house Itochu Corp. was released after serving three years in jail in China, according to the Asahi newspaper. He was imprisoned for espionage in October 2019, it said. 

Read more: China Releases Japanese Man Held For Five Years on Spying Charge

--With assistance from Yuki Hagiwara.

(Updates with Chinese foreign ministry comments in fourth paragraph.)

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