A Japanese man convicted of spying by a Chinese court was sentenced to 15 years in prison Monday, Sino-Japanese sources revealed the same day.

The man, in his 50s, was also fined 100,000 yuan (about ¥1.6 million) by the court in Hainan Province for having illegally obtained state secrets, analyzed them and disseminated them abroad, they said.

Since 2015, at least nine Japanese people have been indicted in China for alleged involvement in spying activities, and this marks the seventh time for a court to render a verdict.

The man, a director of a hot spring development consultancy company in the city of Dalian in northeastern Liaoning Province, was detained in 2017 along with five other Japanese while assisting in geological assessments of potential sites in Hainan and Shandong provinces.

Two of the six were formally arrested later that year for having violated anti-espionage and national security laws, local media reported previously, while the other four were allowed to return to Japan.

The authorities had reportedly retrieved a large amount of classified information, including nearly 80 copies of maps, from the pair's computers and other electronic devices.

Of the two who were arrested, the other man, in his 70s, was sentenced last Friday to a prison term of five years and six months by a court in Shandong.

The issue of the Japanese detainees in China was raised at the summit level when Prime Minister Shinzo Abe visited Beijing in October 2017 and stated that the Japanese government is not engaged in spying activities in the country.