Police in England have uncovered a cryptocurrency mining operation while executing a drugs warrant.

Officers raided a property in Sandwell, near Birmingham, on suspicion that there was a cannabis farm.

“We heard how lots of people were visiting the unit at different times of day, lots of wiring and ventilation ducts were visible,” West Midlands Police said in a statement.

“They are all classic cannabis factory signs.”

A drone also picked up a considerable heat source from above.

However police were stunned to discover 100 computer units running as part of what West Midlands Police described as a “Bitcoin mining operation”.

They seized the IT equipment and found that the operation had been stealing thousands of pounds (dollars) worth of electricity.

No arrests had been made, police said.

“It had all the hallmarks of a cannabis cultivation set-up and I believe it’s only the second such crypto mine we’ve encountered in the West Midlands,” sergeant Jennifer Griffin said.

“My understanding is that mining for cryptocurrency is not itself illegal but clearly abstracting electricity from the mains supply to power it is.

“We’ve seized the equipment and will be looking into permanently seizing it under the Proceeds of Crime Act. No-one was at the unit at the time of the warrant and no arrests have been made — but we’ll be making enquiries with the unit’s owner.”

-with agencies