Computer hackers apparently based abroad have broken into the Bank of Greece’s central data system, with still unknown consequences, a top electronic fraud expert said yesterday.

According to Michalis Mavis, head of OTE state telecom’s system security and risk prevention unit, the attack was mounted through the network of an Italian university — which, however, may just have been broken into by hackers to confound attempts to track them. He did not name the university, and did not specify when the attack took place.

Mavis, who is also the chairman of the Greek Institute for the Prevention of Telecommunications Fraud, told the First International Conference and Fair on Security — a two-day event that opened in Athens yesterday — that the hackers may well have transferred cash from the central bank to other accounts. He said, however, that it had proved impossible for OTE officials to ascertain this, due to strict privacy rules imposed by the Authority for the Protection of Personal Data.

The same hackers, Mavis said, had previously targeted the National Research Foundation’s computer systems, billing the state foundation for millions of drachmas in phone calls to sex lines. According to Mavis, suspicion had initially fallen on NRF employees, who were accused of making the calls from work.

Speakers at the conference also drew attention to the major threat of credit card fraud, while Mavis said some 2,000 Greeks fall victims every day to scams involving Internet sex sites. He said many such sites charge visitors at international phone call rates, resulting in otherwise inexplicably large telephone bills.