By Can Sezer and Birsen Altayli
ISTANBUL (Reuters) - Hackers targeted Turkey's Akbank via the SWIFT global money transfer system in an attack which the bank said had not compromised customer data but would cost it up to $4 million.
Banks globally face a growing threat from cyber attacks, more of which have succeeded since February's $81 million heist from the Bangladesh central bank.
It was not immediately clear how much, if any, money had been stolen from Akbank, Turkey's third-largest listed bank by assets and it would not give any further details beyond confirming it had been targeted in a SWIFT attack on Dec. 8.
Akbank said in a statement on Thursday it had immediately taken preventive measures and informed authorities, that its systems were working properly and there was no loss to customers.
"This has no impact on Akbank's operations or financials. The maximum risk Akbank would face is $4 million," it said, adding that any potential losses would be covered by insurance.
SWIFT, a Belgium-based co-operative owned by both central banks and commercial banks, said it had "no indication that our network and core messaging services have been compromised".
Founded in 1973, SWIFT operates a secure messaging network that has been considered reliable in handling trillions of dollars in daily fund transfers.
But recent attacks involving criminals sending fraudulent payment instructions after gaining access to a bank's SWIFT interface, either by hacking or with the co-operation of local bank staff, underscore how its role as the backbone of international banking also presents a systemic risk.
In February, hackers used stolen Bangladesh Bank credentials to request the transfer of nearly $1 billion from its correspondent account at the New York Federal Reserve and succeeded in moving $81 million to four accounts in Manila.
Shares of Akbank were down 1.1 percent at 7.87 lira by 1407 GMT, compared with a 0.7 percent decline in the Istanbul stock exchange's index of bank stocks.
(Additional reporting by Tom Bergin in London; Writing by David Dolan; Editing by Susan Thomas and Alexander Smith)