Washington  - Heavy fuel oil shipments to North Korea have been cut off because Pyongyang has refused to sign onto a process for ensuring that it is complying with an agreement to dismantle its nuclear weapons programme, the US State Department said Friday.

"This is an action-for-action process, and certainly the United States - and I think this is the understanding of other parties - is that future fuel shipments aren't going to move forward absent a verification regime," spokesman Sean McCormack said.

Negotiations between China, Japan, Russia, South Korea and the United States with North Korea ended in Beijing on Thursday without a verification agreement.

North Korea rejected a compromise proposal because it included terms to allow nuclear inspectors to take soil and waste samples from its nuclear facility in Yongbyon, a process that can determined how much plutonium for nuclear weapons was produced.

North Korea in 2007 agreed to give up its nuclear weapons programme in exchange for economic and energy aid from the five other countries and improved diplomatic ties with Washington.

The United States in August removed North Korea from its state sponsors of terrorism blacklist after Pyongyang disclosed the extent of its nuclear activities. The five other countries in the six- nation talks also want to establish a process for ensuring North Korea provided a truthful declaration.

The chief US envoy, Christopher Hill, has returned to Washington. The impasse is a setback for President George W Bush, who has been trying to secure a deal with North Korea before he leaves office.

McCormack said the five countries would continue consultations and there still remained a chance to come to an arrangement.

"There's the opportunity for North Korea to sign on to this verification protocol. That still exists. We'll see. The ball is in their court," McCormack said. (dpa)