"The power of the North Korean state comes from the nuclear atom. Amid continuing confrontation with the Unites States, the possibility [of North Korea] dropping it remains minute," Kim Jong-nam told the Tokyo Shimbun paper.

North Korea has been subjected to several rounds of UN Security Council sanctions since it declared itself a nuclear power in 2005. The state broke off talks with South Korea, China, the United States, Japan and Russia on its nuclear program in April 2009, after the United Nations Security Council passed a resolution condemning its missile tests.

In late November that year, Pyongyang disclosed to visiting U.S. experts an operational uranium enrichment facility at Yongbyon, prompting fears that the secretive state had again begun developing nuclear weapons.

Before Pyongyang officially declared last year Kim's younger son, Kim Jong-un, heir apparent, Kim Jong-nam was widely speculated to become the country's next leader.

Commenting on the issue, Kim Jong-nam said his father initially opposed the appointment of a successor.

"Even China's Mao Zedong did not have a successor. It is against socialism," Kim Jong-nam, 39, said, adding: "But I understand that this has been done to strengthen the statehood. Instability in North Korea will lead to instability in the region."

He also admitted that living standards in North Korea left much to be desired.

"My heart breaks when I hear news [from North Korea]. I don't think that the living standards [there] are improving. I want North Korea to be stable, its economy to recover and its people to be wealthy," Kim Jong-nam said.