A Japanese man has been arrested for alleged espionage in the northeastern Chinese port city of Dalian, a government source confirmed Tuesday.

The Japanese government had been trying to confirm the validity of a Chinese media report on Monday that Chinese prosecutors have approved the arrest of the man. The source also told reporters that Tokyo has been closely monitoring the treatment of the man by Chinese authorities.

According to Japanese government sources, a Japanese man in his 60s was detained by Chinese authorities in the Liaoning Province city in May and the arrest reported by the Dalian Daily could be in reference to this case.

China has been stepping up its surveillance of foreign individuals and organizations in the name of protecting national security since President Xi Jinping came to power in 2013.