Some of Greece's biggest banks may have to shut and merge with their rivals, it has been claimed.
A European official told the Reuters news agency that Greece's four big banks - National Bank of Greece, Eurobank, Piraeus and Alpha Bank - could be reduced to just two.
European leaders are meeting on Sunday in a bid to strike a financial aid deal with Greece.
Russian President Vladimir Putin, and Greek Prime Minister Alexis Tsipras have spoken to discuss yesterday's No vote in the Greek bailout referendum, the Kremlin has said.
No mention of financial aid was made in the statement.
A Greek government official said Putin had initiated the call, which took place during a break in talks in Athens between Tsipras and political party leaders today, ahead of renewed negotiations with eurozone creditors.
The Greeks have voted to reject the austerity terms demanded by eurozone creditors - so, what happens next?
Greeks have voted to reject the terms of an international bailout, putting it on the brink of a eurozone exit.
Greece's controversial Finance Minister Yanis Varoufakis has released a defiant statement of resignation entitled 'Minister no more!'