SEOUL (REUTERS) - South Korea fired tens of artillery rounds towards North Korea on Thursday after the North fired a suspected projectile towards a South Korean loudspeaker that had been blaring anti-Pyongyang broadcasts, South Korea's defense ministry said.

North Korea did not immediately respond to the South's shots, it said, as tensions rose on the peninsula.

South Korea said its detection equipment had spotted the trajectory of a suspected North Korean projectile launched at around 3:52 pm (0652 GMT), which did not appear to have damaged the loudspeaker or caused any injuries.

The suspected North Korean projectile landed in an area about 60km north of Seoul on the western part of the border zone, the defence ministry said. South Korean residents in the area were ordered to evacuate, according to Yonhap.

South Korea's presidential office said it was convening an urgent meeting of the national security council, Yonhap said.

Tension between the two Koreas has risen since early this month when landmine explosions in the Demilitarised Zone (DMZ) wounded two South Korean soldiers. Seoul accused North Korea of laying the mines, which Pyongyang has denied.

Seoul then began blasting anti-North Korean propaganda from loudspeakers on the border, resuming a tactic that both sides had halted in 2004.

North Korea on Saturday demanded that the South halt the broadcasts or face military action, and on Monday began conducting its own broadcasts.

Thursday's exchange of fire came amid ongoing annual joint US and South Korean military exercises, which began on Monday and which North Korea regards as preparation for war.