The computer networks of three South Korean broadcasters and at least two banks were “paralysed” in what appeared to be a coordinated cyber attack on today, report said.

Authorities in Seoul were not immediately able to pinpoint the cause of the system failures and the national security office declined to speculate on where the attack may have originated, although suspicion immediately fell on North Korea, said a Daily Telegraph report.

“Reports have been made simultaneously, so we have dispatched investigators to the scene,” an official in the National Police Agency’s cyber-terrorism department was reported to have told Yonhap News.

National broadcasters KBS, MBC and YTN reported shortly after 2pm that their computer networks had inexplicably come to a complete halt. Editing equipment had also been affected, affecting broadcasts. Shinhan Bank and Nonghyup Bank reported that their systems had also been affected at the same time.

Just hours earlier, officials of the South Korean intelligence agency accused Pyongyang of carrying out intensive cyber propaganda attacks against the South, designed to damage government policies and encourage social discord.

“The North seems to think of cyberspace as a way to circumvent South Korea’s anti-communist National Security Law, and as a viable weapon to hurt Seoul by spreading disinformation that can weaken public support for policies,” a intelligence source told Yonhap.

To date, Seoul has identified 442 sites and organisations that are dedicated to attacking South Korean interests through the Internet, including Uriminzokkiri, the regime’s main Internet-based media and propaganda site.

This week, the site has posted a new propaganda video depicting an attack on Washington and missiles destroying the Capitol Building.

•Photo, courtesy Telegraph: South Korean soldiers walk near a fence at a military check point.