North Korea is using radio waves to jam GPS signals in South Korea, Seoul said Friday, affecting scores of planes and vessels at a time of elevated military tensions on the divided peninsula.

North Korea is using radio waves to jam GPS signals in South Korea, Seoul said Friday, affecting scores of planes and vessels at a time of elevated military tensions on the divided peninsula.

The North has been sending GPS-jamming signals since Thursday from various locations near the heavily-fortified border, the South’s defense ministry said.

The science ministry said the jamming had so far affected 58 aircraft and 52 ships, although no significant disturbances to flight or navigation had been reported.

"GPS jamming is an act of provocation. We urge the North to stop such provocative acts and behave in a manner that would help improve inter-Korean relations", Unification Ministry spokesman Jeong Joon-Hee told journalists.

In 2010, the South's defense minister warned that North Korea had obtained a Russian-made jamming device capable of disrupting guided weapons systems.

Two years later, during a similar period of cross-border tensions, the South said North Korean jamming activities had forced hundreds of South Korean civilian aircraft and ships to use back-up navigational equipment to avoid compromising safety.

Pyongyang dismissed the allegations as "sheer fabrication."

Tensions have surged this year since the North carried out its fourth nuclear test on January 6, followed a month later by a long-range rocket launch that was widely seen as a disguised ballistic missile test.