SHANGHAI (Kyodo) -- A Chinese court has sentenced a Japanese woman to six years in prison for spying, a source privy to bilateral relations said Saturday.

The Shanghai Intermediate People's Court, which handed down the ruling on Friday, also seized 50,000 yuan ($7,273) in assets from the 57-year-old, who is of Chinese origin, according to the source.

The woman, an executive of a Tokyo-based Japanese language school, was detained in Shanghai in June 2015 on suspicion of engaging in espionage. She was indicted in July 2016.

The source, however, said the specifics of what she did remain unknown.

China has been tightening its watch over foreign individuals and organizations, with arrests of Japanese and other nationals on similar allegations increasing since a counterespionage law came into force in 2014 and a new national security law took effect the following year.

The court in Shanghai has also decided to deport the woman after she serves the sentence, the source said.