A Christian group says a leader of the Association of North Korean Human Right Organizations was recently detained at a Chinese airport for several hours Monday.

According to the Christian relief organization, “Joy of Sharing,” Pastor Suh Kyung-suk and 31 other pastors departed from Incheon International Airport on Monday afternoon for Frankfurt as part of a trip to Europe.

The group was detained at around eight p.m. at Beijing Capital International Airport between flights.

All of the pastors except Suh were released quickly. The organization says Suh was released after midnight Monday, but the group was able to board their two a.m. flight to Frankfurt.

Chinese authorities apparently detained Suh as he has been active in campaigns promoting improved human rights conditions in North Korea and for taking part in a campaign supporting Nobel Peace prize laureate Liu Xiaobo.