A US military reconnaissance plane came under electronic attack from North Korea and had to make an emergency landing during a major military exercise in March, an aide to a lawmaker said Friday.
The aide said the plane suffered disturbance to its global positioning system (GPS) by jamming signals from the North's southwestern cities of Haeju and Kaesong as it was taking part in the annual US-South Korea drill, Key Resolve.
The incident was disclosed in a report that Seoul's defence ministry submitted Thursday to opposition lawmaker Ahn Kyu-Baek of parliament's defence committee, the aide to Ahn told AFP.
Spokesmen for the defence ministry and US Forces Korea declined to comment.
Jamming signals, sent at intervals of five to 10 minutes in the afternoon on March 4, forced the plane to make an emergency landing 45 minutes after it was airborne, the aide quoted the report as saying.
They also affected South Korean naval patrol boats and speedboats as well as several civilian flights near Seoul's Gimpo area, according to the report.
Seoul mobile users also complained of bad connections and the military reported GPS navigational devices malfunctioning as the South and the US were staging the drill, which was harshly criticised by the North.
The communist state has about 20 types of jamming devices mostly imported from Russia and it has been developing a new device with a range of more than 100 km (62 miles) near the heavily fortified border, Yonhap news agency has said.
The North is also believed to have been responsible for the intermittent failure of GPS receivers on naval and civilian vessels along the west coast in August 2010.
South Korea's then-defence minister Kim Tae-Young said at the time that the devices could disrupt guided weapons and posed "a fresh security threat" to Seoul.
The UN's International Telecommunication Union in April urged the North to stop disrupting signals in the South.