The financial regulator said Thursday it will require banks to build a two-pronged network system in a bid to avert cyber attacks after a series of online hackings into some of their websites.

The Financial Services Commission (FSC), the country's top financial watchdog, said it plans to have large banks separate their network systems into two partitions -- one for internal use and the other for online use -- by next year.

Under the measures, banks must split their main operating system first in the next 12 months before gradually splitting the network systems at headquarters and branches, which will likely take a few more years, the FSC said.

The regulator's push for tougher measures came as securing online security at local financial companies surfaced as one of the top policy priorities, following a spate of unidentified cyber attacks on the websites of Nonghyup Bank and Shinhan Bank in late March.

Currently, the state-run Industrial Bank of Korea (IBK) is the only one to have a complete set of separate network systems, while Shinhan Bank runs two different systems at its headquarters. Others have been reluctant of the network expansion citing high costs.

The FSC estimated the costs for splitting the network system at a range of 1-4 billion won, though they may vary depending on each bank's size, it said.

Although there was no leakage of personal data in the March attack, the incidents prompted the authorities to draw up more stringent rules against potential cyber threats as they could paralyze the country's entire online banking system.

Online and mobile banking have become a common means of making easy payments for many Koreans. As of end-March, electronic banking in South Korea accounted for 87.7 percent of the total financial transactions, with its daily amount reaching an average of 33.8 trillion won (US$29.7 billion), FSC data showed.

As cyber attacks are becoming more sophisticated, the regulator is pushing for establishing a consolidated back-up center for data storage, the FSC said.

While there is already a secondary place for banks' data retrieval in the event of a cyber attack or natural disaster, this will be a third rescue center for emergency data recovery, it added.

The FSC said it will most likely be set up as an underground bunker located far away from Seoul for security. Currently, the U.S. and Israel run back-up systems at underground bunkers built in dead mines.

The tougher measures also include giving more responsibilities to the head of the financial firm in case of network failure, as well as reinforcing manpower for cyber security, according to the FSC. (Yonhap News)