A North Korean jamming device capable of disrupting guided weapons poses a fresh threat to South Korea's security, the South's defence chief said on Tuesday.

Defence Minister Kim Tae-Young told parliament that the North had imported Russian equipment to jam South Korea's GPS (Global Positioning System) reception.

"North Korea's GPS jamming is seen as a fresh security threat" as it can disrupt guided weapons, he said.

The North is thought to have been responsible for the intermittent failure of GPS receivers on naval and civilian craft along the west coast from August 23 to 25, Kim said on Monday.

He also said the North was capable of jamming GPS reception over a distance of up to 100 kilometres (60 miles).

"This could impose a serious threat to South Korea's GPS-guided weapons such as missiles and smart weapons," Chae Yeon-Seok, a researcher at the state-run Korea Aerospace Research Institute, told AFP.

In Iraq, US troops used GPS-guided weapons for precision strikes against tanks on roads without damaging other facilities, he said.

"If GPS signals from satellites are jammed, such weapons would lose directions to deliver warheads to targets," he added.

North Korea has modified Russian equipment to make its own version, the Chosun Ilbo newspaper said, adding the regime has been trying to export its GPS interrupter to the Middle East.

The North's GPS interrupter is believed to be effective in preventing US and South Korean GPS-guided bombs and missiles from hitting their target accurately, it said.

The South has pushed for longer-range weaponry to counter the threat from hundreds of North Korean ballistic missiles.

The North has about 600 Scud missiles capable of hitting targets in South Korea, and possibly also able to reach Japanese territory. There are another 200 Rodong-1 missiles which could reach Tokyo.

The North has test-launched intercontinental Taepodong missiles three times.