South Korea issued a warning Thursday after detecting satellite signal disruptions that it said appeared to be coming from North Korea.

   The warning, issued at 7:30 p.m. in Seoul, the adjacent city of Incheon and the surrounding Gyeonggi and Gangwon provinces, came as North Korea discharged a large amount of radio waves to jam Global Positioning System signals in the region, officials said.

   "We've detected signs that North Korea has been sending radio waves to the capital area since a month ago to disrupt GPS signals," a senior government official said, speaking on condition of anonymity. "North Korea had been sending test waves since last month, but today, they discharged the largest amount."

   The disruptions could cause mobile phones to malfunction and affect planes and ships that rely on GPS for navigation.

   No damage has so far been reported in the military or among civilians, officials said.

   Such disruptions have occurred three times since 2010, and all have been blamed on the North.