Investigators acting on a list of account holders with sizeable foreign-based deposits provided by Germany swooped on the bank and examined hard drives containing their account details.
The source said the account holders had been summoned to report to judicial authorities to clarify their situation and avoid potential prosecution.
The clampdown on deposits as large as €12 million ($13.1 million) could net the Greek treasury an estimated €2 billion, the national ANA news agency reported.
Berlin last month passed on details of those under suspicion and holding deposits totalling some four billion Swiss francs ($3.7 billion) on receiving some 10,000 sets of data on accounts held by companies and private individuals from the German state government of North Rhine Westphalia.
“We are carefully going to analyze the data and if need be ask Switzerland for further information,” Greek deputy minister of finance, Trifon Alexiadis, said at the time.
Other similar lists of alleged tax evaders have emerged in recent years in Greece — notably in 2010, when IMF head Christine Lagarde furnished Athens with one.
That list appeared after former HSBC employee Hervé Falciani blew the whistle on tax evaders, leaking the details of some 130,000 people with Swiss bank accounts, notably held with HSBC's private Swiss subsidiary.
Included on the list were the details of some 2,000 Greeks, including several politicians.
Lagarde passed the details on to Athens but the Greek authorities did not launch an investigation into tax fraud, which remains a political hot potato despite the government's promises to crack down on the practice as a condition of landing its most recent EU bailout.