North Korea sends its message South

North Korea has given new meaning to the phrase "selling your neighbour down the river" as propaganda for the communist state has flowed into South Korea.

South Korea is accusing North Korea of floating propaganda leaflets via a river in the first such incident of its kind.

And while it might be more a case of selling ice to an eskimo, the nature of threats within the leaflets has the South Korean government taking things seriously.

The Defence Ministry said it recently discovered dozens of plastic bags, each carrying about 20 leaflets, near a Seoul river close to the tense Korean border.

It says the leaflets contained threats to launch missile attacks on South Korea and praised the leadership of Kim Jong-Un and the North's political system.

A Cold War-style standoff flared after the North's fourth nuclear test in January.

Seoul resumed blasting anti-Pyongyang propaganda broadcasts and K-pop songs from border loudspeakers.

Pyongyang responded by restarting its own border broadcasts and floating balloons carrying anti-South leaflets.