More than 4,000 churches have been closed down over the last month in Rwanda for failing to comply with health and safety regulations, including not being properly soundproofed.
It has affected mostly small Pentecostal churches and a few mosques - some of them operating out of caves or on the banks of rivers.
"This is not being done to prevent people from praying but to ensure the safety and tranquillity of worshipers," Minister of Local Government Jean Claude Musabyimana told state media.
It is the first major crackdown since a law came in five years ago to regulate the proliferation of places of worship.
It requires them to operate in an organised way and in safe environment as well as outlawing their use of loud public address systems.
The legislation also compels all preachers to have theological training before opening a church.
When the law was adopted in 2018 about 700 churches were initially closed.
At the time, Rwandan President Paul Kagame said the country did not need many houses of worship, maintaining that such a high number was only fit for more developed economies with the means to sustain them.
Mr Kagame, who has just won a fourth term in office with 99% of the vote, rules over a tightly controlled society where his critics say there is little freedom of speech.
The ongoing operation targeting churches is being carried out by local urban authorities in partnership with the Rwanda Governance Board (RGB).
The authorities say they are taking a tough line as churches have had five years to fully comply with the regulations.
“The government has taken a stance against proliferation in the houses of worship. We still see cases of dilapidated [structures] and unhygienic conditions,” RGB chief Usta Kayitesi told the New Times news website.
Some of the churches that had been shut down operated in tents, exposing worshippers to risks, Mr Musabyimana said.
So far 4,223 places of worship have been closed, with 427 of those being in caves, reports a privately owned Kinyarwanda language Igihe news site.
The vast majority of Rwandans are Christians but many also follow traditional practices.
Pentecostal churches, often run by charismatic preachers claiming to be able to perform miracles, have grown rapidly in many parts of Africa in recent years.
Some are massive, attracting thousands of worshippers each Sunday, but others are tiny structures built without planning permission.