SEOUL : North and South Korean soldiers exchanged fire Monday across their heavily guarded border in the first such incident in over a year, the South's defence ministry said.

The North Koreans started the shootout by firing machine gun rounds, it said.

"In response, South Korean soldiers fired 10 warning shots from a machine gun. There were no casualties from the shooting," a ministry spokesman said.

"After firing the counter-shots, our side issued an warning through a loudspeaker and demanded an apology. But there was no response from the North Korean soldiers," a spokesman for the South's Joint Chiefs of Staff said separately.

"It was not known immediately whether North Korean troops opened fire by mistake or intentionally," he said.

Cross-border shooting incidents have been rare since a landmark inter-Korean summit in 2000.

The last was on July 31 last year when North Korean soldiers fired towards a South Korean guard post.

No one was hurt.

Monday's shooting took place at about 1:30pm near Inje, 165 kilometres (100 miles) northeast of Seoul.

The two Koreas have been separated by a 248-kilometre-long and four-kilometre-wide Demilitarised Zone since the end of the 1950-53 war. - AFP/ch