North Korea notified South Korea of its plan to conduct live-fire drills near the tensely guarded western sea on Monday, calling for the control of vessels near the region, the Joint Chiefs of Staff said.

The Southwestern Command of the Korean People's Army faxed South Korean Navy's Second Fleet at 8:00 a.m. to announce the fire drills in seven border regions in the Yellow Sea, north of the Northern Limit Line, later in the day.

"North Korea demanded South Korea control its vessels in seven regions north of the NLL before it holds the live-fire drills," the JCS said. "We have banned vessels from entering the training zone for the safety of residents and sailors."

It is rare that the communist state announces a training zone that encompasses all western border regions, though it didn't disclose the specific time of the planned exercise.

The South Korean military has stepped up its guard against possible clashes, looking into Pyongyang's intention behind the latest provocations.

"We consider that the North's announcement contains hostile intentions," Army Col. Wi Wong-seop, the vice defense ministry spokesman, said in a briefing. "(North Korea) is believed to be creating a crisis situation on the Korean Peninsula by raising tensions near the western maritime border."

Seoul officials have been on high alert as some artillery shells fired by the North fell south of the NLL during a 2010 exercise.

The latest move comes as the North Korean military has been stepping up its rhetoric against annual joint drills between South Korea and the United States, firing a series of missiles and rockets in a show of force in recent weeks.

Pyongyang last week fired two mid-range ballistic missiles capable of striking Japan in the latest provocative launches, drawing condemnation from the U.N. Security Council. (Yonhap)