Iranian police have discovered and confiscated 9,404 illegal cryptocurrency mining devices in Tehran since the beginning of the Persian calendar year, which started on March 21. 

Kambiz Nazerian, head of Tehran Electricity Distribution Company, said on Monday that the energy-guzzling devices were discovered by inspectors in different districts of the capital.

In recent years, Iranian authorities have regularly announced the discovery of illegal cryptocurrency mining machines in different parts of the country. Many of these operations were based in public locations such as schools and mosques that receive free or heavily-subsidized electricity.

Cryptocurrencies are created through a process known as mining, where powerful computers compete with each other to solve complex mathematical problems. The process is highly energy-intensive, often relying on electricity generated by fossil fuels, which are abundant in Iran.

Iran has a complex relationship with crypto-currencies, which have helped hide various kinds of illicit trades banned by US and other European sanctions.

However, many reports in Iranian media have indicated that large scale crypto mining has been taking place by influential or well-connected networks and some Chinese companies have also been present in Iran using cheap, subsidized electricity.

A 2021 study found that 4.5 percent of global Bitcoin mining – worth around $1 billion then – was in Iran, leading to pressure on electricity supply in peak times and to repeated government assurances that the sector would be better regulated.