South Korea’s Joint Chief of Staff said its troops returned fire after the North shot at an observation post in the demilitarized zone that separate them.
The rare exchange of fire power occurred even as the United States and China sought to coax North Korea back into talks for resolving the dispute over its nuclear programme.
Colonel Lee Hong-ki, spokesman for the South Korean military, said North Korean soldiers fired four shots in a single burst at a South Korean post. The South answered with a warning broadcast and returned fire with 17 shots.
No one was wounded in the South. There was no immediate comment from the North.
The last time the North and South Korea had exchanged fire was in November 2001.
Its navies also fought along their disputed maritime border in June 2002. Six South Korean sailors and an estimated 13 Northern seamen died.
The shooting was being viewed as a precursor to heightened tensions in the run up to the 50th anniversary of the July 27 armistice that ended the Korean War.
North Korea has in the past raised tensions to attract attention or before climbing down to a compromise or concession.
“The North Koreans have continued to look for ways to remind the United States that it is out there and that they can do damage as a way of trying to draw attention,” Scott Snyder, a Korean expert with the Seoul-based Asia Foundation said.
In Washington, a State Department officials said North Korea appeared ready to resume three-way talks with China and the United States.
Ever since Washington accused the North last year of possessing a secret nuclear weapons programme, it has been under diplomatic pressure to resolve the dispute through talks.