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.
A formal request for a bailout loan with the euro zone's special support fund has been lodged by Greece, a spokesman for the European Stability Mechanism (ESM) confirmed
He said: "The ESM has received the Greek request."
The Eurogroup of finance ministers is set to look at the application, which is formally addressed to its chairman Jeroen Dijsselbloem.
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!'