The fate of four South Korean activists being held in China will likely be high on the agenda during Chinese Public Security Minister Meng Jianzhu’s visit to Seoul later Thursday, diplomatic sources said, as speculation mounts over their possible release.

Meng‘s visit comes more than three months after the activists were arrested in the northeastern Chinese city of Dalian on March 29, apparently for their efforts to help North Korean defectors hiding in China. The group is accused of endangering China’s national security, a serious charge that carries heavy punishment, but no further details have been disclosed, according to officials in Seoul.

South Korean officials and diplomatic sources have made conflicting claims about the fate of the activists. One source said Wednesday they had already been released, while a foreign ministry official said they were still under arrest, with no indication from Beijing as to when they would be freed.

Other sources said China has decided to drop charges against the South Koreans as they wish to keep their activities secret.

Beijing, a key ally of Pyongyang, has been under growing pressure from activists and lawmakers in South Korea and other countries to stop its forced repatriation of North Korean defectors.

Diplomatic sources believe the activists will likely be released and deported from China following Meng‘s visit to Seoul.

The detainees include Kim Young-hwan, a 49-year-old senior researcher for the Seoul-based civic group Network for North Korean Democracy and Human Rights. He was a former South Korean proponent of North Korea’s guiding “juche” philosophy of self-reliance, but he later renounced his pro-North Korean ideology and became active in projects to raise awareness about the North‘s dismal human rights record.

Meng, who doubles as a state councilor, is the first Chinese public security minister to visit Seoul on an official trip since the two countries established diplomatic relations in 1992.

During his three-day stay, he is scheduled to meet with Foreign Minister Kim Sung-hwan and Justice Minister Kwon Jae-jin, among other officials, and discuss cooperation in areas, including consular and immigration services, according to Seoul’s foreign ministry.

Meng is due to leave Saturday after attending the opening ceremony of a Chinese consulate general on the South Korean resort island of Jeju. (Yonhap News)