Four South Korean activists held in China for allegedly helping North Korean defectors there are likely to be released soon.

According to diplomatic sources in Seoul, the four activists, including Kim Young-hwan, a senior researcher for the Seoul-based civic group Network for North Korean Democracy and Human Rights, have already been freed from a Chinese detention center in Dandong. Reports say they are now under the custody of South Korean officials in Shenyang.

Other sources in Beijing also claim talks are underway in China to deport them back to the South.

Meanwhile, China's Public Security Minister Meng Jianzhu is expected to arrive in Seoul on Thursday for talks with South Korea's foreign and justice ministers. His visit has raised hopes for the swift release of the activists.