China has released four of six Japanese nationals who have been detained there since March.
Japanese Chief Cabinet Secretary Yoshihide Suga made the announcement Thursday, but did not provide details on when the men were let go, citing the two who remain in custody. He said the four have returned to Japan.
Three of the Japanese were detained in the eastern province of Shandong, while the others were arrested on the southern island of Hainan. China's Foreign Ministry said the men were being held on suspicion of engaging in "illegal activities," but gave no specific details.
Three of the freed men are employed by a Japanese geophysical company, which says it sent the men to China to work with two local hot springs developers. One of the two men still in custody also works for the firm.
At least five Japanese nationals have been arrested in China since 2015 on suspicion of spying. The two nations have been engaged in a maritime territorial spat over a group of small islands in the East China Sea.