North Korea: Nuclear Arsenal 'Will Be Increased'

North Korea has vowed to strengthen its nuclear capability, keeping up a defiant tone a day after warning it was in a "state of war" with South Korea.

Pyongyang also said it would never abandon its atomic weapons in exchange for aid, describing them as a "national treasure".

The central committee of the ruling Workers' Party, chaired by leader Kim Jong-Un, decided at a meeting that the country's nuclear arsenal "should be expanded and beefed up qualitatively and quantitatively until the denuclearisation of the world is realised", the official KCNA news agency reported.

Tensions have risen sharply since the United Nations tightened sanctions in response to the North's nuclear and missile tests. Joint US-South Korean military drills south of the border also angered Pyongyang.

On Saturday, the North declared it was in a "state of war" with the South and warned Seoul and Washington that any provocation would swiftly escalate into an all-out nuclear conflict.

During their meeting, members of the committee also decided to develop a light water reactor as part of a civilian nuclear power industry to ease electricity shortages, KCNA said.

The North in 2010 disclosed the existence of a uranium enrichment facility and a light water reactor, purportedly to generate power.

Experts said it could easily be reconfigured to make fuel for nuclear weapons, supplementing the existing plutonium weapons programme.

In April 2009, the North formally abandoned six-party talks which offered it economic and security benefits in return for denuclearisation.

On Sunday it reiterated that its atomic weapons were not a bargaining chip.

"They are a treasure of a reunified country which can never be traded with billions of dollars," KCNA quoted the committee as saying.

The meeting vowed to push for nuclear development and boost both agriculture and living standards.

The committee also said it wanted to develop space science and technology, including the launching of more advanced satellites, including communications satellites.

Pyongyang says its long-range rocket launches are aimed at putting satellites into orbit for peaceful purposes. The United States and other nations say the real purpose is to test banned ballistic missile technology.

As tensions have escalated in recent weeks, Washington has maintained a notably assertive stance, flying its nuclear-capable B-52s and B-2 stealth bombers over the South.