North Korea insisted Thursday it needs atomic weaponry to deter a US nuclear threat, and vowed never to give up its right to launch rockets as part of what it called a peaceful space programme.

Washington's aim is to "eliminate the political ideology and system our people have opted for", Foreign Minister Pak Ui-Chun told a regional Asian gathering in Cambodia, according to a summary given to reporters by his delegation.

North Korea's launch of a long-range rocket on April 13 heightened regional tensions and sank a deal with the United States reached on February 29.

Under that agreement, the North had agreed to freeze its uranium enrichment plant and suspend nuclear and missile tests, while the US promised 240,000 tonnes of food aid.

The US and its allies described the rocket launch as a disguised missile test, while the North said its aim was only to put a satellite into orbit. The rocket failed soon after takeoff.

Pak, according to the summary, told fellow foreign ministers at the ASEAN Regional Forum that it was the US which scuppered the February 29 deal and was to blame for tensions on the Korean peninsula.

The United States, Japan and South Korea held a joint meeting on Thursday which warned that "any provocation by North Korea... will be met with a resolute and coordinated response from the international community".

It also expressed "deep concern about the well-being of the North Korean people and the grave human rights situation in North Korea".

Pak, in his comments to the gathering in Phnom Penh, cited the use of a North Korean flag as a target during a major US-South Korean live-fire exercise in the South as a "clear proof of the hostile intent of the US".

It said the North would never give up its sovereign right "to explore and utilise the outer space and to develop nuclear energy for peaceful purpose" by building light water reactors to generate electricity.

Pyongyang says its uranium enrichment plant is intended to fuel light water reactors to generate power. Scientists say the plant could easily be reconfigured to produce bomb-making material, supplementing its current plutonium programme.

Pyongyang's atomic deterrent had helped maintain the regional nuclear balance and reduced the risk of atomic war, it said. "We need to safeguard our sovereignty from constant nuclear threats of the US."

The paper reiterated calls for a peace treaty with the United States to replace the armistice which ended the 1950-1953 Korean War.

Six-party talks, which envisage a peace treaty and other benefits if the North scraps its atomic weaponry, have been stalled since December 2008.