North Korea has threatened to resume long-range missile testing and demanded that the United States apologise for calling the reclusive country "an outpost of tyranny", official media reported.

The threat follows a February 10 announcement in which North Korea officially said for the first time it had nuclear arms and was pulling out six-way disarmament talks with the United States, China, Russia, Japan and South Korea.

The Korean-language version of a Korean Central News Agency (KCNA) report late on Wednesday quoted a Foreign Ministry statement saying North Korea had a right to test-fire missiles, despite a moratorium that has been in place for six years.

North Korea did not feel bound by the 1999 moratorium on missile testing, reached when it was in non-proliferation talks with the administration of then US President Bill Clinton, the state news agency said.

The North said its dialogue with Washington ended with the arrival of the Bush administration in 2001 and that meant it had the right to resume missile testing.

"There is now no binding force for us on the moratorium on missile testing," the Korean-language report said. "We are not legally bound by an international treaty, or anything else on the missile issue." North Korea has criticised the Bush administration for first branding it part of an "axis of evil" and more recently describing it as an "outpost of tyranny".

"The US should apologise for his above-said remarks and withdraw them, renounce its hostile policy aimed at a regime change in DPRK (North Korea) and clarify its political willingness to co-exist with DPRK in peace and show it in practice," the report said.