Pyongyang: North Korea on Friday warned rival South Korea and the rest of the world not to expect any change after Kim Jong Il's death, sending a tough message as Kim's young son strengthened his position as supreme leader.

North Korea's powerful National Defense Commission said that the country would never deal with South Korean President Lee Myung-bak, a conservative who stopped a no-strings attached aid policy toward the North in 2008, and that it would unite around new leader Kim Jong Un.

The stern message came a day after North Korea ended official mourning for Kim Jong Il and declared Kim Jong Un supreme leader of the ruling party and military at a massive public memorial for the elder Kim. The top levels of government have unified around Kim Jong Un, who is in late 20s, in the wake of his father's death on December 17.

"We declare solemnly and confidently that the foolish politicians around the world, including the puppet group in South Korea, should not expect any change from us," the National Defence Commission said in a statement. "We will never deal with the traitor group of Lee Myung-bak."

It said the "evil misdeeds" of the Lee administration reached a peak when it prevented South Koreans from visiting North Korea to pay respects to Kim Jong Il, except for two delegations led by a former first lady and a business leader, both of whose husbands had ties to North Korea.

The North's statement is a warning for Seoul not to take the new leadership lightly, said Koh Yu-hwan, a North Korea expert at Seoul's Dongguk University.

"It is also raising the stakes in case the South wants better relations so Pyongyang can extract greater concessions" during any later talks, Koh said. He added that it's "too early to say the North is dashing hopes for reforms."

(Agencies)