North Korea hit back at the UN Security Council Saturday over its recent censure of Pyongyang for launching several rounds of short-range ballistic missiles.

In a statement carried on North Korean official media the foreign ministry described the UN criticism as "absolutely intolerable" and defended the missile launches as a response to "madcap war manoevres" by the United States.

North Korea regularly fires off missiles and rockets, but the frequency of the recent tests -- six in less than three weeks -- is unusual.

UN resolutions bar North Korea from conducting any launches using ballistic missile technology.

On Thursday the UN Security Council officially condemned North Korea for the launches, and urged it to "fully comply" with UN restrictions.

But Pyongyang has shown little appetite for backing down over the launches.

"All the military measures taken by the Korean People's Army including tactical rocket firing are an exercise of the right to self-defence" to protect the country from US aggression and nuclear threats, the foreign ministry said, according to the report.

The statement added that the reclusive state was determined to "bolster up its muscle" to protect itself.

"No matter how fair-minded and just one may be, one is bound to fall victim to big powers if one is weak, and it is possible to protect genuine peace only when one builds its muscle strong enough to deter any force from provoking one," it said.

North Korea often conducts tests and drills as a show of displeasure, and the latest missile launches on Sunday were fired after Pyongyang denounced an upcoming South Korean-US naval exercise.

Previous tests had preceded Chinese President Xi Jinping's state visit to Seoul, and were seen by some analysts as a show of pique at his decision to make Seoul rather than Pyongyang his first stop on the peninsula.

In between the recent launches, Pyongyang has also made several peace overtures to Seoul, including a proposal for both sides to halt all provocative military activity.

The South dismissed the offer as "nonsensical" in the light of the North's nuclear weapons programme and reiterated that the annual joint military drills with the US are non-negotiable.