The State Department says the deal under which North Korea is to end its nuclear program in return for aid and diplomatic benefits cannot go any farther without an agreement to verify disarmament steps.  Four days of talks in Beijing on a verification protocol have ended without agreement.

Bush administration officials had hoped that the final weeks of their tenure would yield an agreement that would propel the six-party North Korea disarmament process into its conclusive stage.

But they say North Korea resisted a draft verification plan supported by all the other participants, and the process is stalemated unless there is a change of heart by Pyongyang.  

North Korea has partially disabled the reactor complex that produced plutonium for its small arsenal of nuclear weapons in return for energy aid from the other parties.

After difficult negotiations, Pyongyang in June made a declaration of its nuclear activities and assets upon which further disarmament steps and benefits for the communist state would be based.

But efforts to come up with a plan to verify the North Korean disclosure have stalled, amid a dispute between Washington and Pyongyang over whether samples can be taken from North Korean nuclear sites for outside analysis.

Officials say in this week's Beijing talks, North Korea would not accept a draft Chinese plan that allowed sampling among other verification steps.  At a news briefing, State Department Spokesman Sean McCormack said the process can go no further unless Pyongyang accepts the draft.

"North Korea said it could not, at that meeting, accept the draft, could not initial the draft," he said. "All the parties said o.k., let us adjourn the meeting, go back to capitals, think about it, and we will keep working this process.  But this is an indication, a public indication, of how central to this process we view verification.  Verification is absolutely essential to the process.  And frankly, it is not going to be able to move forward without a verification protocol."

North Korea has said sampling would violate its sovereignty and has denied U.S. assertions that it verbally committed to the procedure at talks in October.  Spokesman McCormack says the North Korean agreement was explicit.

"We got a commitment," he said. "And we have very, very precise notes about those commitments, and we committed those to paper also in the form of a memorandum for the record, if you will.  So we know what was committed to in those discussions.  Now we will see if North Korea is willing to take the next step and formalize that among the six."

A Chinese communiqué from the heads-of-delegation meeting said the six parties will hold another meeting at an early date, but it is unclear whether they will convene again before the change in U.S. administrations in January 20.

At the White House, spokeswoman Dana Perino said the negotiating process had deteriorated because of North Korea's refusal to put verification pledges in writing, and said the United States will re-think the reciprocal concessions upon which it is based.

But the State Department's McCormack said he was unaware of any consideration of returning North Korea to the U.S. list of state sponsors of terrorism, from which it was removed in October.