It was confirmed by the President of Greece, “that the strength of banks is very weak right now.” Multiple reports including the President of Greece has reported that on Monday alone nearly $898 Million or €700 million Euros were withdrawn from Greek banks.

http://z6mag.com/business/greek-bank-run-showing-more-signs-as-greece-citizens-line-up-at-atms-169333.html

Greek President Karolos Papoulias was told by the nation’s central bank chief that financial institutions are worried about their survival as Greeks pull out euros amid a deepening political crisis. Central bank head George Provopoulos told Papoulias that Greeks have withdrawn as much as 700 million euros ($891 million) and the situation could worsen, according to the transcript of the president’s meeting with party leaders on May 14 that was published yesterday. “Provopoulos told me that of course there’s no panic but there’s great fear which can evolve into panic,” the president
said.
http://www.bloomberg.com/news/2012-05-15/greek-president-told-banks-anxious-as-deposits-pulled.html