A passenger ferry is seen leaving Incheon Port, May 30, in this file photo. Yonhap

North Korea attempted to jam GPS signals near the western sea border for the fourth consecutive day Saturday, according to the South's military.

The military detected the jamming signals directed toward the islands near the Northern Limit Line in the West Sea, the de facto western maritime boundary between the two Koreas, starting at about 6 a.m., according to a South Korean military official.

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

The North's GPS jamming attempts are the latest in a series of provocative acts this week.

The latest jamming attacks began Wednesday, a day after North Korea sent hundreds of balloons carrying trash and manure across the border to the South in retaliation to anti-Pyongyang leaflets sent by activists in the South.

The move followed Pyongyang's failed attempt to launch its second military spy satellite into orbit Monday night.

On Thursday, the North conducted artillery drills involving what it called super-large multiple rocket launchers. (Yonhap)