The South Korean government has a "strong suspicion" that North Korea conducted yesterday's cyber attack on several major businesses, according to the country's publicly funded news agency.

"(The government) is closely analyzing the incident with all possibilities open, while bearing a strong suspicion that North Korea conducted the attack," an anonymous spokesperson told Yonhap News.

Earlier today, Korea Communications Commission (KCC) linked the attack to a Chinese IP address. Yonhap cited unnamed experts as saying that "the North has used Chinese IPs for cyber attacks in the past".

Yesterday morning, the IT systems of three TV broadcasters, three banks and two insurers unexpectedly crashed. Some of the systems displayed images of skulls, the BBC reported, suggesting it was a cyber attack.

A group calling itself "Whois Team" claimed responsibility for the attack on social networks.

KBS, Korea's largest broadcaster, told Yonhap that it "recovered our mainstay network related to programming and advertising this morning, and normalised our service. But we are still working to recover around 5,000 personal computers that came under the attack, and our Web site is still inaccessible."

Last week, the North Korean government accused the US and South Korea of "intensive and persistent cyber attacks after Internet services were cut off in the country.