"From now on, the six-way talks should become a forum to discuss comprehensive measures to realise denuclearisation of the Korean peninsula in a practical and fair manner," a foreign ministry spokesman said in a statement published by the North's official Korean Central News Agency.

Washington believes North Korea possesses one or two crude bombs and may have reprocessed enough plutonium from spent fuel rods at its Yongbyon nuclear complex for half-a-dozen more.

The spokesman said the North's nuclear arsenal would deter Washington from waging war with Pyongyang, and said future talks should also focus on the US' nuclear threat to the Korean peninsula, according to Yonghap news agency.

"Six-party dialogue can bear fruits only when it is used to seek ways of rooting out the US nuclear threat in and around the Korean peninsula," the spokesman said.

Pyongyang declared on February 10 that it had nuclear weapons and withdrew indefinitely from the six-party disarmament negotiations.

Since abandoning talks, North Korea has sent mixed signals on its willingness to return to the negotiations, with leader Kim Jong-Il saying Pyongyang would resume dialogue if "conditions" are met.

Last week North Korean Premier Pak Pong-Ju held talks in Beijing with China's top leaders and reiterated Pyongyang was ready to resume negotiations on its nuclear programs, but only when conditions were right.

North Korea has demanded an end to US "hostility" and rewards for dismantling its nuclear weapons drive.

But "time has gone for talking about a give-and take like the freeze of nuclear weapons program and compensation at the six-party talks," the North's spokesman said.

South Korea said the North's latest statement would "not be helpful" to six-party talks.

"It's not surprising," a senior South Korean official said, adding the statement ran counter to an agreement at previous talks to make the Korean peninsula free of nuclear weapons.

South Korea has clarified its position that North Korea should not become a nuclear armed country, he said. "There is no reason to change this position."

Christopher Hill, Washington's chief delegate to the talks, said in Hong Kong that the United States would consider other options if North Korea refused to return to talks.

"One option that is not available to us is to walk away from it," Hill said,

Hill said efforts are being made by different countries, especially China, to get North Korea to rejoin talks, which offer diplomatic and economic rewards in return for nuclear disarmament.

"We all need to keep working on this. I don't think any of us could be satisfied with any efforts until we get this thing going."

Earlier this month US Secretary of State Condoleezza Rice also said Washington would consider "other options" if the talks fail, but made it clear that a military attack was not one of them.

The two Koreas, the United States, China, Russia and Japan have met three times to try to resolve the nuclear standoff that erupted in 2002 when the United States accused the North of operating a secret uranium-enrichment program.