The European Central Bank said Greek debt will temporarily be ineligible as collateral for loans after Standard & Poor's yesterday cut Greece's credit rating to "selective default."

The ECB "has decided to temporarily suspend the eligibility of marketable debt instruments issued or fully guaranteed by the Hellenic Republic for use as collateral in Eurosystem monetary policy operations," the Frankfurt-based ECB said in a statement today. "This decision takes into account the rating of the Hellenic Republic as a result of the launch of the private sector involvement offer."

While the ECB's risk management rules prevent it from accepting collateral deemed to be in default, the central bank will resume taking Greek debt once a 35 billion-euro ($47 billion) guarantee scheme agreed by European governments comes into force in mid-March. A reduction in Greece's credit rating was anticipated after the country agreed a debt write-down with private sector investors, seeking to reduce national debt to 120 percent of gross domestic product by 2020 from 160 percent last year.