The ECB approves the provision of emergency liquidity for Greek banks but froze it one week ago, leading to the imposition of a 60-euro-a-day limit on cash withdrawals and the closure of banks. Its Governing Council talk on Monday about the approval of continued support.

"I am convinced that what we've done so far is right and conforms with our rules. But one has to make new decisions every time. The development in Greece does not make this easier for us, I'm afraid," Nowotny, who also heads Austria's central bank, told ORF radio, commenting on the provision of Emergency Liquidity Assistance (ELA).

"It has become apparent that Greek banks have a tendency to run out of liquidity," he said, adding, however: "One cannot keep banks shut indefinitely."

(Reporting By Shadia Nasralla; editing by John O'Donnell)