Fresh fire heard as North Korea warns South

South Korea's military reported sounds of distant artillery fire from within North Korea, as the North issued a warning over it's neighbours planned war games.

South Korean television said the shells appeared to have landed north of a disputed maritime border in North Korean waters. The military does not believe the firing was aimed at the South.

The reports came as the North said that the planned joint military exercises between South Korea and the US were pushing the peninsula to the 'brink of war'.

The USS George Washington, a nuclear-powered US aircraft carrier, is one of a number of ships heading to the Yellow Sea to take part in the drills, which are set to begin on Sunday.

North Korea warned it will "wage second and even third rounds of attacks without any hesitation if warmongers in South Korea make reckless military provocations again".

At least four people died on Tuesday when the North surprised Seoul by shelling the island of Yeonpyeong.