In the mean time, the European Central Bank's governing council on Wednesday decided not to increase the liquidity lifeline to cash-strapped Greek banks, a Greek banking source said.
The bank is "ready to intervene as and when necessary," the source said, adding that "no other decision was taken" at the ECB meeting. It was the ECB's decision on Sunday to refuse to increase emergency funding for Greek banks that pushed Athens to close lenders and impose the capital controls.
Eurozone finance ministers, meanwhile, were meeting again to discuss Greece's position. Some European officials said the new Greek offer, made in a letter Tuesday night, wasn't good enough and that a deal remained impossible in any case before the referendum. Tsipras' letter said his government was prepared to accept creditors' proposals, subject to certain amendments.