China’s capital, Beijing, is probing cryptocurrency mining operations to assess their impact on energy consumption, Reuters reported Thursday. 

The Beijing Municipal Bureau of Economy and Information Technology sent out an emergency notice to the city’s data centers on Tuesday asking them to report any involvement in crypto mining operations, according to a document obtained by Reuters.

Data centers are required to report the amount and share of power used up by the mining of bitcoin and other cryptocurrencies, the notice said. 

The probe was directed by city authorities, and recipients of the notice included the country’s three largest telecommunications operators, an official of the bureau told Reuters.

Crypto mining has recently come under fire for consuming large amounts of energy. A number of mining hubs including Iran, Abkhazia and now China have started cracking down on crypto mining operations over energy concerns.

In March, Inner Mongolia, an autonomous region in China, declared it would force crypto mining businesses to close by April.  

Despite China’s ban on crypto exchanges, the country remains a mining hub, contributing up to 65% of the global mining hashrate (the computing power used to mine cryptocurrencies). After a series of accidents in Southern China’s coal mines, resulting power outages caused the global bitcoin hashrate to drop dramatically, as miners in the region rely on cheap energy from coal.