The prosecutor's office in the central Russian city of Voronezh has asked a local Muslim leader to provide information about people who attend the local Islamic center, RFE/RL's Tatar-Bashkir Service reports.
The move follows the center's recent victory in a months-long court battle to build a mosque in the city.
The Islamic center is formally subordinate to the Spiritual Board Of Muslims of the European part of Russia.
Aynaz Safiullin, a leading member of the local Muslim community, told RFE/RL on December 1.
"[They asked] how many people attend Friday prayers, who they are, and where they are from. They asked for their phone numbers and addresses. They were also interested in how we pay the rent for our Islamic center and where we get money for it."
Voronezh Oblast police press service deputy head Igor Sushkov said asking for information about Muslims living in Voronezh does not violate the law on investigations.
But human rights activists say doing so contravenes the law on protection of personal data.
The Voronezh Islamic center rents a building in the northern district of the city. It has just started building a mosque after an eight-month court battle.
"The Prosecutor-General's Office, members of the Public Chamber of the State Duma, and local residents did their best to prevent us from building a mosque," Safiullin said.
But the Islam center won the case.
Some 150-200 Muslims attend Friday Prayers and 300-500 people come to the center on Muslim holidays. The center plans to start classes in Tatar, Arabic, and reading the Koran.