The United States on Wednesday ruled out recognizing North Korea as a nuclear power after the communist state said it was willing to join global disarmament efforts if treated as an equal partner.

"We will not accept North Korea as a nuclear-weapon state. Its current path is a dead end," State Department spokesman Philip Crowley told reporters.

He renewed US calls on North Korea to comply with a six-nation agreement to give up its nuclear program in return for aid and security guarantees.

"If it comes constructively back to the six-party process, then there are opportunities available to North Korea for a different relationship with the United States," Crowley said.

"But they cannot expect a different relationship until they take specific actions first," he said.

North Korea's foreign ministry offered not to take part in a nuclear arms race or to produce weapons "more than it feels necessary" if Pyongyang is allowed into disarmament efforts with the status of a nuclear-weapons state.

North Korea made the pitch as US President Barack Obama intensifies his campaign for the eventual elimination of nuclear weapons.

North Korea was the only declared nuclear power which Obama did not invite last week to a major summit on nuclear security.

The Obama administration also revised the US nuclear posture to state for the first time that the United States would not threaten a nuclear attack against a country without nuclear weapons and compliant with the Non-Proliferation Treaty, no matter what the provocation.

North Korea has tested two nuclear bombs and in 2003 withdrew from the NPT in a showdown with the United States over its weapons programs.

North Korea last year agreed to return to six-nation talks -- which also include China, Japan, Russia, South Korea and the United States. But it has since said that it first wants a permanent peace treaty with Washington.