Days after Chinese officials blocked Catholics from seeing the pope in South Korea, it's still unclear who was behind the action or why it was taken.

Reports say about 50 Catholic clergy and laypeople were stopped at Chinese airports earlier this week.

Experts on the Chinese church say the travel bans were likely the work of overzealous local Communist Party bureaucrats responsible for religious affairs.

However, the central government in Beijing has offered no clarification on the matter, underscoring its discomfort about how to deal with the Vatican.

The sides have no formal ties and are locked in a dispute over who has the right to appoint bishops and overall religious freedoms under the officially atheistic ruling party.