Ku Kyo-young from the state-run Korea Communications Commission said the latest assault began around 6:30 p.m. Thursday.
He said one of the affected sites belongs to the government, the other six are private. Some are still working normally despite the attacks.
Earlier Thursday, the country's leading computer security company warned that another wave of cyber attacks was expected later in the day.
South Korea's spy agency suspects North Korea is behind the series of attacks that have triggered Web site outages in South Korea and the United States.
(Copyright 2009 by The Associated Press. All Rights Reserved.)
Watch report here