North Korea was suspected of a massive wave of cyber attacks on U.S. and South Korean government and corporate Web sites in 2009.
Signals intended to disrupt GPS and other wireless communications were detected originating in North Korea's border cities of Kaesong and Haeju on Friday, Yonhap news agency quoted military officials as saying.
The signals resulted in the disruption of some mobile phone functions that use GPS signals, such as network-based clocks, electronics devices used by artillery units in the South, and some equipment at commercial organisations, Yonhap quoted the officials as saying.
South Korea's Defence Ministry did not comment on the report.
The signal-scrambling may have been intended to disrupt the joint military drills by South Korean and U.S. forces that run until March 10, Yonhap said.
In a separate attack on personal computers, malicious software have been used in cyber attacks on some government agency Web sites since Friday, but no serious damage has been reported.
Telecommunications authorities and the police are working to determine the source of the software.
(Reporting by Jack Kim; Editing by Daniel Magnowski)