The ECB move, which analysts said was aimed at stepping up pressure on Athens to adhere to the commitments of its EU/IMF bailout, will force Greek banks to turn to their national central bank for Emergency Liquidity Assistance (ELA) funds. Those funds will be more expensive than funds available in the ECB's regular liquidity operations.

The ECB said the collateral exclusion was due to the expiration of a temporary 35 billion euro scheme agreed with Greece and euro zone leaders whereby the ECB would continue to accept Greek bonds after they went into default this year.

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European and IMF officials are due to visit Athens next week to decide whether Athens merits another tranche of aid from its latest bailout package and analysts said the ECB move was designed to step up pressure on Greece ahead of the visit.