Since the last auction on August 5, Athens and its international creditors agreed a third huge international bailout for the debt-stricken country, worth 86 billion euros over three years.
However there has not been boost in investor confidence as early elections were called for September 20 after Alexis Tsipras resigned as prime minister last month following a serious split within his radical-left party Syriza over the bailout.
Athens sold 812.5 million euros of six-month bills last month.
Greece has not had access to long-term capital markets since the start of its debt crisis in 2010, with the exception of two brief returns to medium-term markets.