North Korean leader Kim Jong Un vowed not to use nuclear weapons unless his country was attacked by another nuclear power.

Kim's comments came during the second day of the Congress of the Workers' Party of Korea (WPK), where he appeared to be consolidating his grip on power. The congress announced that it would bestow its top title on Kim, although he is already the "supreme leader" of the party and the country.

"As a responsible nuclear weapons state, our republic will not use a nuclear weapon unless its sovereignty is encroached upon by any aggressive hostile forces with nukes," the state-run news agency, KCNA, quoted Kim as saying.

"And it will faithfully fulfill its obligation for nonproliferation and strive for the global denuclearization."

After North Korea conducted its fourth nuclear test in January and subsequently launched a long-range rocket into space, both in defiance of past Security Council resolutions, the UN body passed renewed, and tougher, sanctions on the rogue state.

Even China, North Korea's closest ally, expressed exasperation with the North's insolent behavior, and backed the Security Council's new sanctions regime.

Continuing nuclear program

North Korea responded by continuing its nuclear and missile development activities. Officials claim to have successfully reduced the size of a nuclear warhead and launched a submarine-based ballistic missile.

Kim said the country would continue to build and launch satellites, which the United States and South Korea view as a disguised test for long-range missiles.

In his statement, Kim went on to say that his country wanted to reduce tensions with its enemies, chiefly South Korea and the US, although he did not identify them by name.

But he called on the South's allies to respect the sovereignty of the DPRK, the initialism for the Democratic People's Republic of Korea, the North's official name.

"The WPK and the DPRK government will improve and normalize the relations with those countries which respect the sovereignty of the DPRK and are friendly towards it, though they had been hostile toward it in the past," Kim said.

Kim's proposal is likely to get a chilly response in both Washington and Seoul, where leaders have repeatedly called on North Korea to dismantle its nuclear program as a precondition for peace talks.

Officials in Washington and Seoul say it appears that the North is preparing another nuclear test.

The two Koreas fought a bloody civil war in the early 1950s that ended with an armistice in 1953. But the two sides never signed a peace agreement, so, technically, they remain in a state of war.

bik/bw (Reuters, AP, AFP)