Costas Vaxevanis was in court on a misdemeanour charge of violating data protection laws, after the weekend publication in Hot-Doc magazine of a list of alleged depositors at an HSBC bank in Switzerland. His trial was postponed until Thursday.
The published names were allegedly taken from data on 24,000 HSBC customers that the bank reported stolen in 2010, potentially exposing many international clients to prosecution by tax authorities if they failed to declare the assets in their home countries. The bank said a former IT employee with HSBC, identified by French authorities, had obtained the information.
Greek prosecutors say the more than 2,000 Greek names were given to Greece's government by French authorities.
The list — which also was published Monday by Greece' top selling daily newspaper, Ta Nea — has been dubbed by the Greek media as the "Lagarde List" after former French Finance Minister Christine Lagarde. She now serves as the managing director of the International Monetary Fund.
Former government officials were recently questioned in parliament for allegedly failing to investigate the Greek list for potential tax fraud.
Vaxevanis, who has not been detained, defended his actions after leaving court Monday.
"I'll say something that's very simple: Journalism means publishing something that others are trying to hide. Everything else is public relations," he said. "The public prosecutors' office has shown a special interest in its dealings with me. I don't know why this is the case, but I accept it."
Greece, which has been surviving on rescue loans since 2010, has faced persistent criticism from international creditors for failing to effectively limit tax evasion.
In Brussels, EU Commission spokesman Simon O' Connor declined to comment on Monday about the publisher's arrest. But O'Connor said, "It is essential that the fight against tax evasion in Greece is intensified. All possible cases of tax evasion must be fully investigated by the competent authorities ... and this particularly true at a time when many Greek citizens are being asked to make significant sacrifices in the effort to ensure the sustainability of Greece's public finances."
Greece's government is currently negotiating with its international creditors over a euro13.5 billion ($17.6 billion) package of new austerity measures as the public endures the country's sixth straight year of recession, with 25 per cent unemployment.
AP writers Raf Casert in Brussels and Frank Jordans in Berlin contributed to this story.