US President George W Bush has said North Korea must abandon its alleged nuclear weapons programme if it is to have a viable future.

He was speaking after the US, South Korea, the European Union and Japan agreed to halt fuel aid to the impoverished Communist state as an anti-nuclear sanction.

The only option... is for North Korea to completely and visibly eliminate its nuclear weapons program

George W Bush

"The only option... is for North Korea to completely and visibly eliminate its nuclear weapons program," the president said in a written statement.

But he also appeared to hold out an olive branch to Pyongyang, saying the US could still revive a suspended initiative to "improve the lives of the North Korean people".

Diplomats meeting in New York under the auspices of the Korean Peninsula Energy Development Organisation (Kedo) decided on Thursday that a 42,000-tonne shipment of fuel currently on its way to the North should be the last.

"North's Korea's clear violation of its international commitments will not be ignored," said Mr Bush.

The nuclear dispute flared into life on 16 October when the US announced that the North had admitted to having a programme for producing highly enriched uranium - a key ingredient in nuclear weapons.

South ups pressure

On Friday South Korea's Deputy Foreign Minister Lee Tae-shik said it was "quite united" with its allies and "pleased" with the decision to cut off supplies.

Many in South Korea oppose aid to the North

The official also confirmed that his government would continue to hold talks with Pyongyang.

A senior Southern official quoted by Associated Press said the onus was now on the North to respond.

"The ball is in the court of North Korea," he said.

He added that the South wished to "carry on putting more pressure on North Korea so they understand the seriousness of all countries involved".

South Korea and Japan had previously expressed doubts that stopping oil deliveries will persuade North Korea to terminate its nuclear weapons programme.

They feared it would instead lead to a revival of an earlier, plutonium-based nuclear programme.

Turning the tap off

Under a 1994 accord designed to limit North Korea's nuclear ambitions, North Korea agreed to freeze its nuclear programme in return for 500,000 tonnes of fuel oil a year in aid.

Washington considers that Pyongyang nullified the 1994 pact when it reportedly admitted to a US envoy that it was trying to build nuclear weapons. The North itself has not publicly commented on the admission.

"Future shipments will depend on North Korea's concrete and credible actions to dismantle completely its highly enriched uranium programme," said the statement from Korean Peninsula Energy Development Organisation.

North Korea says it will only scrap its nuclear programme if the US signs a non-aggression treaty.