One of two South Koreans detained by Chinese authorities late last month with a group of North Korean defectors has been released and returned home, Seoul\'s foreign ministry official said Tuesday. The two men, who had also defected from North Korea before they settled in the South, were held by China for questioning. They were detained while apparently trying to help the group of North Koreans reach South Korea. \"One of the two South Korean nationals was released and returned home last night,\" the ministry official said, speaking on the condition of anonymity. South Korean authorities were investigating the released man, the official said. Initial news reports said that 35 people, including the two South Korean nationals, had been detained, but the number of the detainees appears now to be about 20, the official said. A diplomatic source in Seoul said that Chinese Vice Premier Li Keqiang plans to visit South Korea on Oct. 26-27, indicating that the release of the South Korean man may be tied to the planned visit. South Korea has urged China not to repatriate the North Korean defectors to their homeland, although it remains uncertain whether Beijing will heed Seoul\'s calls. \"We clearly emphasized to China that the (South) Korean government takes this issue very seriously and that the Chinese government must ensure the defectors are not repatriated against humanitarian perspectives and their will,\" foreign ministry spokesman Cho Byung-jae told reporters last week. As North Korea\'s only major ally, China does not recognize North Korean defectors within its borders as refugees and regularly deports them back to North Korea, where they are said to face severe punishments ranging from torture to public execution. More than 22,000 North Koreans have defected to South Korea since the end of the 1950-53 Korean War, fleeing poverty and political repression in their homeland. Many reach the South after crossing the border into China. Human rights activists believe more than 100,000 North Koreans may still be in China in search of a safe route to South Korea.