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.
Greek Prime Minister Alexis Tsipras has said a deal with the country's creditors would be struck 48 hours after a 'No' vote in the upcoming referendum on the bailout proposals.
Tsipras said: "If the 'No' prevails and the 'No' is the strongest, I reassure you, the next day I will be in Brussels, and a deal will be signed."
European officials and the Greek opposition have warned a 'No' outcome Sunday could be tantamount to a decision to leave the euro.
A strong 'No' vote, Tsipras argued, would help Greece win a new deal with the eurozone's rescue mechanism that would include terms to make the country's 320 billion euro (354.7 billion US dollar) national debt sustainable.
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!'