North Korea publicly admitted Thursday it possesses nuclear weapons and vowed not to return to six-nation talks aimed at persuading it to halt its nuclear ambitions. "We have manufactured nuclear weapons for self-defense to cope with the Bush administration's ever-more undisguised policy to isolate and stifle the DPRK (North Korea)," the official KCNA news agency quoted an unnamed Foreign Ministry spokesman as saying. The spokesman was quoted as saying that North Korea was suspending its participation in the nuclear talks for an "indefinite period" if "America's hostile policy" was not changed. However, the statement said Pyongyang remained committed to dialogue. "The DPRK's principled stand to solve the issue through dialogue and negotiations and its ultimate goal to denuclearize the Korean Peninsula remain unchanged," China's Xinhua news agency quoted the spokesman as saying. In the past, U.S. diplomats have said North Korea privately acknowledged possessing nuclear weapons. But such a clear public announcement that it had already manufactured an undetermined number of nuclear arms was never made. "The U.S. disclosed its attempt to topple the political system in the DPRK at any cost, threatening it with a nuclear stick. This compels us to take a measure to bolster its unclear weapons arsenal in order to protect the ideology, system, freedom and democracy chosen by its people," said the statement reported by Xinhua. Three previous rounds of the nuclear talks - involving North and South Korea, the United States, China, Japan and Russia - produced no breakthroughs. But Seoul had recently expressed hope that North Korea may be prepared to join the discussions as early as March. The six nations have tried to coax the reclusive communist state into halting its nuclear weapons programme in exchange for economic, food and energy aid. A fourth round of six-party talks scheduled to take place before the end of September last year was cancelled after North Korea boycotted, citing a continuing hostile U.S. policy.