Costas Vaxevanis, the publisher of investigative magazine Hot Doc, could be in court again as early as next month after the prosecutor found "legal faults" in the original verdict handed down on November 1st.
The journalist will now be tried by a panel of three judges, the source said on condition of anonymity.
The first hearing had been presided by a single judge.
Vaxevanis faces a maximum three-year prison sentence for publishing an alleged copy of the so-called 'Lagarde list', a document containing the names over 2,000 Greek HSBC account holders in Switzerland.
The list was originally leaked by an HSBC employee in Geneva and passed to Greece in 2010 by France's then finance minister Christine Lagarde, who now heads the International Monetary Fund.
The list enabled authorities in France, Spain and Britain to recuperate millions of euros in lost tax revenue, but Greek authorities treated it as
stolen data and failed to pursue the case.
Vaxevanis' first trial had turned into a major embarrassment for the government which was accused of trying to bury the issue and muzzle the
A number of media unionists and politicians testified on his behalf, including the head of the International Federation of Journalists, Jim
Bumelha, who called the trial an "absurd farce".
The affair has resurfaced amid British press reports over another list of some 8,500 people with accounts at the HSBC branch of the Channel Island tax haven of Jersey.
Finance Minister Yannis Stournaras on Thursday wrote to his British counterpart George Osborne to request information on the list, which
reportedly includes nearly 100 Greek account-holders.