(FRANKFURT) - The European Central Bank decided on Wednesday to extend by two weeks and increase the amount of emergency liquidity available to Greek banks, a bank source said.

"The increase has been approved," a eurosystem central banking source, who declined to be identified, told AFP.

The source added that the ceiling for emergency liquidity assistance -- or ELA -- to Greek commercial banks had been raised to 68.3 billion euros ($77.5 billion) from 65 billion euros previously.

The move comes a day before Greece is expected to request an extension of up to six months on a European loan agreement without the strings of a full-blown bailout.

Two weeks ago, the ECB effectively shut off Greek banks from a key channel of financing by saying it would no longer accept Greek sovereign bonds as collateral for loans in its normal refinancing operations.

Greek debt has a junk credit rating and, under ECB rules, should not qualify as collateral for loans.

But Athens had been granted a special waiver to that rule as long as it was deemed to be in compliance with the terms of its 240-billion-euro EU-IMF bailout.

The ECB announcement that it was lifting that waiver was seen as a severe blow to Greece and caused Athens' borrowing costs to soar.

It kept an emergency liquidity assistance (ELA) channel open, but lending under this facility is more expensive and it is the Greek central bank that is on the hook for any potential losses.

Should Athens and its eurozone partners fail to agree on a new debt deal, the ECB may be forced to review the provision of ELA funding, which, under ECB rules, is made available to solvent banks.

The ECB council will re-examine its ELA assistance for Greek banks at its next meeting in two weeks' time.