Iranian authorities have locked the doors of a prominent mosque in the southern city of Shiraz that is the base of an opposition ayatollah, RFE/RL’s Radio Farda reports.

The closing of the mosque is apparently aimed at silencing Ayatollah Seyyed Ali Mohammad Dastgheib, who is based there.

Dastgheib is a prominent supporter of opposition leader Mir Hossein Musavi. He is also a member of Iran’s powerful Assembly of Experts, the body charged with selecting and supervising Iran’s supreme leader.

Dastgheib has used the mosque as a platform to deliver sermons fiercely critical of the Islamic republic’s current regime.

The same eyewitness told RFE/RL the mosque “has a long history as a center of the people’s opposition to the shah of Iran.”

The Islamic republic’s government has long seen mosques as bastions of support. In this case, however, a mosque is at the center of opposition to it.

During the shah’s rule, the opposition used mosques to rally support against the government. But the shah reportedly never ordered the closure of a mosque for political reasons.