TAIPEI (Taiwan News) – The Straits Exchange Foundation has asked China for information about the detention of a Taiwanese couple allegedly proselytizing for the Unification Church, reports said Saturday.

According to a letter sent by their relatives, they were detained on Jan. 12. The husband was later released on bail but the wife is still in detention, with both unable to return to Taiwan, per CNA.

SEF said it sent a letter to its Chinese counterpart, the Association for Relations Across the Taiwan Straits, requesting assistance. It also informed the Ministry of Justice and the Criminal Investigation Bureau.

At a news conference Friday, SEF Spokesperson Li Pao-wen (黎寶文) emphasized that taking part in religious exchanges with China was legal, but the communist country banned proselytizing. Religious activities in China mostly took place in the context of foundations or alliances, he said.

In October, three elderly Taiwanese followers of the Yiguandao religious movement were arrested in Guangdong Province. Despite requests from Taiwan to release them, they still have not been allowed to return home.