Gref also told reporters that Sberbank's loan-loss provisions in Ukraine made up around 70 percent of its potential losses, according to Reuters.

Read alsoUkraine's central bank: Russian banks in talks on sale of Ukrainian assetsUkraine recently decided to impose more sanctions on Sberbank and other Russian state-owned banks operating in Ukraine – part of a broader flare-up in tensions linked to separatist regions of eastern Ukraine which are backed by Russia.