North Korea staged GPS jamming attacks in waters near South Korea's northwestern border islands for a third straight day on Friday, the South's military said, in the latest in a series of provocative acts this week.

The military detected the jamming signals from about 8 a.m. directed toward the islands near the Northern Limit Line in the Yellow Sea, the de facto western maritime boundary between the two Koreas, according to a South Korean military official.

The latest attempt has not hindered the military's operations, the official said, although similar attempts the previous day led to glitches in the navigation systems of fishing boats and passenger ships in the waters.

The military detected the Thursday attack shortly after the North launched 18 rounds of multiple rocket launchers toward the East Sea.

The North's first GPS jamming attempts this week took place Wednesday, as it sent hundreds of balloons carrying trash and fecal matter to the South after vowing to do so in retaliation against anti-Pyongyang leaflets sent by activists in South Korea. (Yonhap)