SEOUL North Korea is responsible for the disruption of GPS signals in some part of South Korea's capital region last week that caused malfunctions in mobile phones, media reports quoted officials as saying on Sunday.
Communications officials could not say whether the North was behind separate cyber attacks on government Web sites including that of the presidential Blue House and the Defense Ministry since Friday that slowed or disabled them for hours.
If the North were responsible for either or both of the incidents, it could mark an escalation of tension between the rivals already high from two attacks on South Korean territory last year and ensuing exchange of threats of war and retaliation.
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 organizations, Yonhap quoted the officials as saying.
South Korea's Defense 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.