The United States is working to secure a UN Security Council statement condemning North Korea's newly disclosed uranium enrichment programme, a senior official said Wednesday.

Robert Einhorn, the State Department's special adviser for nonproliferation and arms control, was speaking after talks with Wi Sung-Lac, South Korea's chief envoy to stalled six-party talks on the North's nuclear disarmament.

"We are working hard to get a Security Council presidential statement that makes clear that North Korea's uranium enrichment programme is a violation of both UN Security Council resolutions and the September 2005 six-party joint statement," he said.

The North agreed in 2005 to scrap its atomic programmes in return for aid, diplomatic and security benefits, but the deal broke down amid accusations of bad faith from both sides.

In 2006 and 2009 Pyongyang tested atomic weapons, attracting UN sanctions, and last November disclosed the uranium enrichment plant.

Experts say this could give Pyongyang a new way to build nuclear weapons, in addition to its plutonium-based operation.

South Korea wants the Security Council to address the uranium programme before any new six-party talks.

But China, the North's main ally, wants to revive the talks which it chairs and which also include Russia, the United States, Japan and the two Koreas. It says the uranium programme should be handled at that forum, which last met in December 2008.

Last month China blocked the publication of a UN report criticising the uranium programme.

Einhorn also ruled out the possibility of US tactical nuclear weapons being redeployed in the South to cope with the North's nuclear threats.

"We have no plan, we have no intention to deploy US tactical or other nuclear weapons in South Korea. Moreover, we don't believe there is any military need to do so," he said in answer to a question.

"The United States and South Korea can have a robust, effective deterrence without deployment of US nuclear weapons in South Korea," Einhorn said.

"The United States has a range of nuclear delivery capability offshore that can provide very strong extended deterrence... without the need for nuclear weapons belonging to the United States actually on South Korean soil."

The United States withdrew its atomic weapons from the South in 1991, a year before the two Koreas signed a denuclearisation deal.

But some conservative Seoul politicians have been calling for their return in the face of what they call the North's repeated provocations.

Einhorn arrived Tuesday for a four-day visit, leading a team of US officials who will continue discussions on a new civilian nuclear cooperation agreement between Seoul and Washington.

South Korea has no nuclear weapons but relies on nuclear power plants to generate some 35 percent of its electricity.

A 1974 nuclear cooperation accord with the US which expires in 2014 prevents South Korea from reprocessing fuel from its civilian plants.

But the South now has a radioactive waste stockpile of 10,800 tonnes and is running out of storage space.

The two sides are holding a second round of talks on rewriting the nuclear cooperation pact, after discussions in Washington last October.

At those talks they agreed to launch joint research into Seoul's demand to adopt "pyroprocessing" technology, considered by some to be less conducive to proliferation.