Bolton said that 10 years ago North Korea pledged a nuclear freeze under the 1994 Agreed Framework before breaking its word and deciding to "flip a switch and unfreeze its programs."

"We have a saying: 'Fool me once, shame on you. Fool me twice, shame on me.' We will not be fooled again," said Bolton, undersecretary for arms control and international security.

Last month at six-party talks on the nuclear standoff in Beijing, Pyongyang demanded rewards in return for a freeze which its says would be a first step in a process leading to the dismantling of its nuclear facilities.

Bolton was speaking ahead of a summit meeting later Wednesday between Japanese Prime Minister Junichiro Koizumi and South Korean President Roh Moo-Hyun expected to focus on ways to end the 21-month-old nuclear standoff.

Speaking to university students here, Bolton ruled out a reward to North Korea for a freeze and said the Stalinist state should follow the Libya model.

"Our experience with Libya shows that a freeze is unnecessary, and moreover, would simply delay the time when the people of North Korea could reap the benefits of rejoining the international community," said Bolton.

Libya agreed in December to dismantle the country's nuclear, chemical and biological warfare programs and renounce the pursuit of such weapons. In return, Washington lifted most sanctions against Libya in April.

Though Washington appeared to soften its stand during six-party talks in Beijing last month, Bolton said no specific rewards would be offered to North Korea for complying with US demands for the complete dismantling of all nuclear programs.

"The principle, though of not rewarding outlaw regimes merely for coming back into compliance with their past obligations is an important one for the United States to uphold. It is not only anathema to our values -- it is a bad policy," he said.

He said that the experience of Libya should make it clear to North Korea that it stood to gain by agreeing to scrap its nuclear programs.

"Let there be no doubt, the case of Libya has shown concretely the benefits that can flow when leaders of isolated regimes make the strategic choice to invest in their countries' future, and not in weapons of mass destruction."

The stand-off over North Korea's quest for nuclear weapons erupted in October 2002 when the United States accused Pyongyang of operating a nuclear weapons program based on enriched uranium, violating the 1994 nuclear freeze of its separate plutonium producing program.

Three rounds of six-way nuclear talks bringing together the United States, the two Koreas, China, Japan and Russia have been held in Beijing in an effort to resolve the impasse with a fourth round scheduled for September.

North Korea has denied running the uranium program and Bolton said it was unclear whether Kim Jong-Il had made the strategic decision to give up his nuclear weapons drive.

"So there is no misunderstanding -- North Korea's continue denial of its uranium enrichment program precludes a solution to this problem," he said.

WAR.WIRE