SEOUL, April 14 (Yonhap) -- Prosecutors have launched an internal probe into a computer network glitch with a leading lender that crippled its online financial transactions for more than two days causing massive inconveniences to millions of customers, officials said Thursday.

   Customers of the National Agricultural Cooperative Federation, or Nonghyup, were unable to withdraw cash or use online banking services after the shutdown of the bank's computer system began around 5 p.m. on Tuesday.

   Some services, including automated teller machines and Internet and phone banking, returned to normal but credit card and check card services remained crippled as of Thursday afternoon, according to the bank's officials. They said that the service issues are expected to be normalized by Thursday night.

   The cause of the incident remains unknown. The bank said the shutdown could be attributable to an employee of a subcontractor in charge of managing the computer system. His laptop allegedly issued malicious orders to damage the operating system and major computer files of a key computer server of the bank.

   On Wednesday, the Seoul Central District Prosecutors Office sent two investigators to the headquarters of Nonghyup in downtown Seoul and secured the laptop computer and other related materials, officials said.

   The investigators were analyzing the materials to see if professional hackers were involved in the network malfunction.

   Meanwhile, the country's financial watchdog Financial Supervisory Service also launched an independent inquiry into Nonghyup on Thursday to figure out whether the lender complies with financial transaction rules in managing the network system.

   The breakdown is triggering public concerns about the safety of network systems at financial companies as it occurred several days after a serious hacking incident at Hyundai Capital Services Co.

   brk@yna.co.kr
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