South Korean police and officials are investigating the shutdown of computer networks at several major broadcasters and banks. The incident comes days after North Korea blamed the South and US for a cyber attack.
Servers at television networks YTN, MBC and KBS and two major banks, Shinhan Bank and Nonghyup, were affected Wednesday, police and the government said.
Officials at MBC and KBS, South Korea's public broadcasters, said their companies shut down at 2 p.m. (0500 GMT), but that the incident was not immediately causing any damage to their TV broadcasts.
The state-run Korea Information Security Agency confirmed that at least five South Korean companies were experiencing computer outages.
North Korea is believed to be behind two major cyber attacks in 2009 and 2011 that caused network crashes at government agencies and financial institutions in the South.
Last Friday, Pyongyang said it had been the victim of "persistent and intensive" hacking by South Korea and the US that took several of its official websites offline for nearly two days.
Tension between North and South Korea is at its highest level in years following the North's nuclear test last month and the United Nations sanctions that followed.
dr/rg (AP, AFP, Reuters)