A Chinese scholar indicted on charges of spying for Japan has been sentenced to six years in prison in China.

Yuan Keqin, a former professor at the Hokkaido University of Education in Japan, was detained in May 2019, when he was in his homeland for a temporary stay. He was later indicted on charges of being involved in long-term spying at the request of Japan's intelligence agency.

Sources close to Yuan said he received the sentence in January at a court in Changchun, Jilin Province in northeastern China.

Yuan reportedly plans to appeal to a higher court, but details of the ruling are unknown.

Asked about Yuan's current condition in a news conference on Tuesday, China's foreign ministry spokesperson Wang Wenbin said, "I'd refer you to competent authorities for the specifics."

Fellow researchers and others say he is innocent and are calling for his immediate release.