North Korea has staged live-fire artillery exercises near its disputed Yellow Sea border with South Korea amid rising tensions, military officials in Seoul said on Wednesday.
The Joint Chiefs of Staff office said batteries on the west coast fired dozens of shells into the North's waters on Tuesday.
It said the firing came from the regions of Haeju and Ongjin near the Northern Limit Line sea border, where deadly naval clashes occurred in 1999 and 2002.
"The shells all landed within the North's waters. We took the firing as part of their routine winter military exercises," a spokesman for the office told AFP.
The North has increasingly exposed its once heavily-camouflaged batteries along the west coast to the South's monitoring, he said.
Fears of a border clash have grown since the North in late January cancelled all peace accords with the South, including one recognising the sea border as an interim frontier.
The North's military announced last week it is "fully ready" for war with the South.
Seoul's defence chief last week told parliament his troops would target North Korean launch sites if South Korean ships came under missile attack in the Yellow Sea.
But he said Seoul would try to avoid a full-blown war by launching a brief and limited counter-attack.
The North is angry at conservative South Korean leader Lee Myung-Bak, who scrapped his predecessors' policy of engagement with Pyongyang and virtually unconditional aid.
The communist state said on Tuesday it is preparing to launch a satellite, a move the United States and its allies believe is a pretext for a long-range missile test.