Her original remarks provoked laughter from an audience of foreign policy experts and students at the Council of Foreign Relations in Washington on Wednesday.

Rice said Pyongyang had agreed to a verification protocol but had refused to write down some of its negotiators' verbal assurances clarifying the document's "ambiguities".

Fuel aid deal

Six-party talks broke down over the issue last month, but Rice seemed positive that the US, South Korea, and Japan still had leverage over the impoverished nation under a deal which promises fuel aid in exchange for nuclear concessions.

"I think that within the context of the six-party talks, you ultimately will get a verification protocol that allows us to deal with a lot of very troubling activities"

Condoleezza Rice,
US secretary of state

"... the fuel oil shipments that they need, they need not just from the United States but also from South Korea, since South Korea has made clear that their relationship with North Korea depends in part on how denuclearisation goes," she said.

Rice also defended the negotiations, saying that, as a result, North Korea had not produced any plutonium since 2005 and had begun to disable its nuclear complex at Yongbyon.

She said it had also turned over thousands of pages of documents as well as some samples that "have led us to be more suspicious of some things that they might be doing".

Rice predicted that there would eventually be progress on the verification issue.

"I think that within the context of the six-party talks, you ultimately will get a verification protocol that allows us to deal with a lot of very troubling activities," she said.

"This is a process that still has a lot of life in it ... North Korea negotiates this way sometimes in ups and downs."