Relations between North and South Korea are expected to take a further turn for the worse when the South Koreans publish the results of an international investigation into how one of their navy ships was destroyed with the loss of nearly 50 lives.

South Korea's foreign minister let slip to reporters that it was "obvious" that North Korea was responsible for the sudden explosion on board the ship.

Sue Lloyd Roberts has rare access to the secretive North Korean state. She reports now from both sides of the demilitarised border.

Broadcast on Wednesday 19 May 2010.