South Korea says senior officials are meeting counterparts from North Korea at the Panmunjom truce village later this morning.

The meeting, at the abandoned village on the border of the two countries, comes as a deadline set by North Korea for its southern neighbours to take down loudspeakers broadcasting propaganda is set to expire today.

North Korea had in the last few hours reiterated on its official news agency that it is ready for all-out war.

South Korean President Park Geun-Hye ordered her commanders to be ready:

Earlier this week, Seoul said North Korea fired a shell across the border into South Korea, which responded with multiple rounds of artillery fire.

Kim Jong-Un declared a "quasi-state of war" after convening an emergency meeting of the communist country's military leaders, Yonhap reported North Korean TV as saying.

The North had earlier threatened military action if the South continued pumping propaganda into the North across the border using loud speakers.

Anti-Pyongyang statements have been broadcast across the frontier in recently. The North is believed to have been aiming the shell at one of the loudspeakers.

The suspected projectile landed in an area of the demilitarised zone (DMZ) around 60km north of Seoul.

In response, South Korea fired tens of 155mm artillery rounds at the location where the shell came from, the country's defence ministry said.

There were no reports of any injuries on either side of the border.

North Korea denied provoking the exchange of fire, accusing Seoul of using what it called a "nonexistent pretext".

The US Department of Defence said it was monitoring the Korean Peninsula closely and the UN said it was following tensions "with serious concern".

About 28,500 American troops remain stationed in South Korea, with the US having retained bases following the end of the Korean War in 1953.

The three-year Korean conflict was ended by a ceasefire, rather than a peace treaty, technically maintaining a state of war.