Computer networks at two major South Korean banks and three top TV broadcasters went into mass shutdown today, paralysing bank machines across the country and prompting speculation of a cyber attack by North Korea.

SOUTH Korean intelligence officials believe North Korea or pro-Pyongyang forces committed cyber attacks that paralysed major South Korean and US government websites, aides to two lawmakers said yesterday.

North Korea was today blamed for sophisticated cyber attacks that paralysed major US government websites.

A widespread and unusually resilient computer attack that began on July 4 knocked out the websites of several US government agencies - including some responsible for fighting cyber crime, it emerged today.