European Central Bank chief Mario Draghi assured euro zone leaders on Tuesday the ECB would do the necessary to keep Greek banks afloat until an EU summit on Sunday that will seek a deal on further aid to Greece, German Chancellor Angela Merkel said. Speaking at a news conference after an emergency summit of euro zone leaders, Merkel said she was "not exaggeratedly optimistic" of a solution to rescue Greece on Sunday but the summit had been called "because we think the situation is so dangerous". Asked if Greece could crash out of the euro zone if it failed to put forward convincing reform proposals, she said Sunday's summit would decide whether to open negotiations on a two-year programme for Athens.