AFP - South Korea expects North Korea to launch a rocket on Saturday if the weather is good, President Lee Myung-Bak said Friday while warning that it was "not in their benefit".

Speaking to a small group of journalists in London, Lee reiterated that Seoul would be ready to send an envoy to its northern neighbour, if the reclusive state's leaders were willing to accept one.

Asked when South Korea expected the rocket to be fired, he told a small group of journalists in London it depended on weather conditions. "If they think it's suitable for them it's going tomorrow."

Lee, speaking a day after world leaders gathered for a G20 economic summit in London, said South Korea would exercise "perseverance and patience" to get NKorea to change.

"If North Korea is ready and willing to receive a special envoy from South Korea, of course we've always been ready to send one," he added.

Asked if the timing of North Korea's rocket launch was linked to the succession of North Korean leader Kim Jong-Il, he said "there may be a correlation" between the two.