Some Catholics who recognize the authority of the Holy See choose to worship clandestinely due to the risk of harassment from authorities. Several underground Catholic bishops have been reported disappeared or imprisoned, and harassment of unregistered bishops and priests is common. There are reports of Catholic bishops and priests being forced by authorities to attend the ordination ceremonies for bishops who had not gained Vatican approval. Chinese authorities also have reportedly pressured Catholics to break communion with the Vatican by requiring them to renounce an essential belief in Roman Catholicism, the primacy of the Roman Pontiff. In other instances, however, authorities have permitted Vatican-loyal churches to carry out operations.