North Korea says sea border is illegal

North Korea says the maritime border where the sea battle with South Korea took place was illegal and should be abolished.

It has refused to apologise for the skirmish in which four South Korean sailors died.

The South Korean military claim North Korea suffered about 30 casualties.

"The government will take necessary steps so the people can engage in their business without concerns," said South Korean President Kim Dae-jung, who has urged his military to be more vigilant.

Kim has traveled to Japan to watch the World Cup soccer final and meet Japanese leaders. He was expected to return to Seoul on Tuesday.

The fight broke out after two Northern patrol vessels accompanying fishing boats crossed the sea border and one opened fire after ignoring warnings to retreat, South Korean officials said.

North Korea, however, accused Southern boats of provoking the battle by entering communist territory.