Intelligence analysts are still investigating who was behind the cyber attacks that began over the Fourth of July weekend.

The cyber attack caused a surge of Web site outages in the U.S. and South Korea.

Officials said that nearly 90 IP addresses in 16 countries were affected in the cyber attacks. South Korea, the United States, Japan and Guatemala were among the countries attacked by a computer virus.

Seven more attacks were launched against South Korean Web sites on Thursday.

The Korean National Intelligence Service briefed lawmakers on reasons why North Korea might be behind the attacks.

"So far, North Korea was not included among the 16 countries' IP addresses," said Park Young-Sun, a member of the intelligence committee.

Park said Thursday that a senior intelligence official told her the North is suspected, because it earlier warned about intolerance for South Korean and U.S. cyber warfare.

Still, the agency said it is too early to to conclude that the North is responsible and investigations were still underway.