Special investigators have seized about 3,500 illegal cryptocurrency-mining units operating from rented buildings in Bangkok and Nonthaburi and stealing vast amounts of electricity.
The crypto miners were connected directly to outside power lines and over the past two years had illegally drained about 500 million baht's worth of electricitiy from the state grid, Justice Minister Somsak Thepsutin said on Wednesday.
Speaking at the Department of Special Investigation (DSI), Mr Somsak announced the seizure of about 3,500 crypto-mining units from 41 commercial buildings, following an investigation that started in February last year.
The minister said the hardware was smuggled into the country from China and then installed in the buildings. They had been connected directly to the state's electricity transmission network. There were no meters and they paid no power charges.
In each building there were about 100 of the devices, which operated around the clock. The building supervisors paid only 300-2,000 baht in power charges a month for each building.
"The buildings actually consumed power worth 300,000-500,000 baht a month, and the Metropolitan Electricity Authority lost about 500 million baht in revenue through this illegal consumption of electricity," Mr Somsak said.
About 20 people were arrested for maintaining the mining units and officials were questioning them to learn more about the network and who ran it.
The crypto miiners had earned about 35 baht per device per day. Over the past two years, they generated about 100 million baht, the justice minister said.
"This is only the tip of the iceberg. The 41 buildings belonged to only one network operated by these illicit businesses that exist nationwide. There are more places where power is sourced illegally to feed cryptocurrency mining," Mr Somsak said.
Investigators would find out if any electricity authority employees colluded with them, he said.
DSI director-general Trairit Temahiwong said gangs involved in drugs and online gambling used cryptocurrency mining to launder money. He said four of the searched buildings had been damaged by fires because the crypto mining units had overheated.