Top nuclear envoys from the United States and South Korea held talks Saturday on ways to bring North Korea back to disarmament negotiations, a day after the North claimed to have succeeded in enriching uranium.

Stephen Bosworth, the U.S. special representative on North Korea, met with Wi Wung-Lac, South Korea's chief nuclear negotiator, in Seoul.

Bosworth did not comment on details of the meeting, pending a press briefing on Sunday.  But South Korea's state-run news agency Yonhap quoted an official as saying the nuclear envoys discussed a joint response to North Korea's recent nuclear threats and conciliatory gestures.

On Friday, North Korea said it has reached the last stage of enriching uranium, a process which, if completed, would give it a second means of building a nuclear bomb.

In a letter to the United Nations Security Council, North Korea's U.N. ambassador, Sin Son Ho, said Pyongyang also is continuing to weaponize plutonium.
The ambassador said North Korea is prepared for both sanctions and dialogue, adding that if some permanent Security Council members decide to seek further sanctions against the North as a first step, it will bolster its nuclear deterrence first and think about resuming talks afterwards.

South Korea's Foreign Ministry called Friday's developments "regrettable."  

U.S. State Department spokesman Ian Kelly said Friday the United States is very concerned that North Korea is moving closer to the weaponization of nuclear materials.

The U.S. has repeatedly called for North Korea to return to six-party talks on its nuclear program.  North Korea quit negotiations with China, Japan, Russia, South Korea and the U.S. earlier this year to protest U.N. condemnation of a long-range missile test.  North Korea says it will only hold talks with the U.S.

North Korea has recently made a series of conciliatory gestures, including the release of two detained American journalists.

Some information for this report was provided by AFP and AP.