Russian security officials arrested several scientists working at a top-secret nuclear power plant for alleged mini-crypto-currencies.
The suspects tried to use one of Russia's most powerful supercomputers to extract Bitcoins, the media said.
The Federal nuclear center of Sarov, in western Russia, is a reserved area.
The center's press service said: "There was an unauthorized attempt to use IT facilities for private purposes, including so-called mining."
The supercomputer was not supposed to be connected to the Internet – to prevent intrusions – and once the scientists tried to do it, the nuclear center's security department was alerted. They were delivered to the Federal Security Service (FSB), the Russian news service Mash says.
"As far as we know, a criminal case against them was initiated," the press service reported to the Interfax news agency.
Cryptocurrencies like Bitcoin are not based on centralized computer servers. People who provide the processing power of the computer to the crypto-currency system, to allow transactions to take place, can get rewards in Bitcoin.
During the Cold War, the first nuclear bomb of the USSR was produced in Sarov, during the government of Joseph Stalin.
The top secret city was not even marked on Soviet maps and for the Russians special permits are still needed to visit it.
What is Bitcoin?
Putin, power and poison: the elite Russian FSB spy club
Sarov is surrounded by a closely guarded land of no people, with barbed wire fences to keep the curious away.
There are suspicions that the radioactive polonium 210 used to kill the former FSB agent Alexander Litvinenko in London in 2006 came from Sarov.
The Federal Nuclear Center employs up to 20,000 people and its supercomputer has a capacity of 1 petaflop, the equivalent of 1,000 billion calculations per second.
Crypto-currencies in mining require great computational power and huge amounts of energy.
There have been reports of some other industrial facilities in Russia used for cryptocurrencies and a business man has bought two power plants for the business. (link in Russian).
BBC Monitoring reports and analyzes news from TV, radio, web and print all over the world. You can follow the BBC monitoring on chirping is Facebook.