China's Human Rights Watch (HRW) has claimed that a well-known legal rights activist disappeared after being questioned by Beijing airport police on September 14.
Cao Shunli was barred from boarding a flight to Switzerland and since then she was not seen, the BBC reports.
Cao, who has advocated for the right of petitioners, was planning to attend a United Nations human rights training course in Geneva.
Director at China's HRW Sophie Richardson said the member of the Human Rights Council should speak out against China's systematic suppression of activists, who are trying to take part in the human rights reviews.
Earlier, Cao has served two terms in Chinese labour camps as a result of her activism.