LONDON (AFP) - Greek savers could lose at least 30 per cent of their bank deposits which could be seized to help shore up the country's banking system as fears grow of financial collapse, the FT reported Saturday.

Depositors with over €8,000 (S$12,000) in the bank may be made to take a "haircut" similar to those taken by Cypriot account holders in 2013, when uninsured funds were seized to stabilise the financial sector, the FT said, quoting bankers and businessmen close to negotiations.

"It would take place in the context of an overall restructuring of the bank sector once Greece is back in a bailout programme," said one of the sources.

Greek Prime Minister Alexis Tsipras has called a referendum to asks Greeks whether they are willing to swallow tougher austerity measures in return for bail-out funds from its creditors, the International Monetary Fund, the European Commission and the European Central Bank (ECB).

Greek banks have been shut since Monday, and the system faces collapse if the ECB declares the banks insolvent should Greece refuse to pay back its debts.