MOSCOW: Cyber attacks have cost Russian companies and citizens up to 3.6 trillion roubles ($49 billion) this year, the country's largest lender Sberbank said.

Russia has encouraged its citizens to switch to bank cards and limit cash use to try to crack down on the shadow economy, but the number of crimes linked to bank cards has shot up by 500% this year, the interior ministry has estimated.

Stanislav Kuznetsov, Sberbank's deputy chairman, who oversees security and services, told Reuters private business and ordinary Russians were the main targets of cyber attacks, as the state security services are better protected.

"The private sector is the most vulnerable: everything from the clients' accounts to financial data and tender documents are targeted: there are 2.3 million darknet accounts operating in Russian and offering the stolen data," he said.

Russian-speaking cyber criminals operate from Germany, Ukraine and Venezuela, as well as Russia, said the state-controlled Sberbank, which runs its own cybersecurity unit BI.ZONE to provide IT protection and cyber defence for the bank and for others.

While banks, including Sberbank are better protected compared with other parts of the economy, phone fraud - when the client is asked by a person claiming to be a bank employee to provide a card's data - is becoming more common, Kuznetsov said.

He estimated Russians may lose as much as 10 billion roubles from phone fraud this year alone. He did not provide data for 2019.

The Russian central bank recorded more than half a million unauthorised operations across bank accounts in the country last year, which saw 6.4 billion roubles stolen from private and corporate bank accounts.