Russian banks holding deposits in the Central Bank of Russia (CBR) were hacked this year for RUB2bn ($31mn), CNN reported, quoting unnamed CBR officials.

"We were lucky to return some of money," one central bank spokesperson was quoted as telling the US cable news network. The report cited Symantec cyber security specialists as saying that the global banking system has been under sustained attack from a sophisticated hacking group called Lazarus that has been linked to North Korea.

The hackers had targeted RUB5bn at the CBR but 3bn was recovered, the central bank official told CNN. Other details of the attack were not disclosed, although it is said to have been similar to other attacks recently reported in Equador, Bangladesh, Vietnam, and Philipinnes. 

However, the Russian central bank's press service on December 3 told TASS news agency that claims that its correspondent accounts had been hacked to the tune of two billion rubles "are not true to life". Instead, the RUB2bn in question were aggregate losses of Russian commercial banks and their clients for the whole year of 2016, the CBR said.

Earlier that week, Russian media reported that the country's Federal Security Service (FSB) domestic intelligence service warned that foreign security services were planning cyber attacks on Russian banks "across dozens of cities" on December 5 to test a larger plan to destabilise the Russian financial system.