North Korea says it has stopped disabling its nuclear facilities, accusing the US of reneging on a six-party disarmament deal.
Work was suspended on 14 August, a foreign ministry spokesman is quoted as telling the state news agency KCNA.
North Korea says it took the step because the US failed to remove it from a list of state sponsors of terrorism.
But the US says it wants to agree more stringent verification processes before it does so.
North Korea finally submitted a long-delayed account of its nuclear facilities to the six-party talks in June - and was N Korea to expel southern workers ...
Six-party talks on North Korean denuclearisation end ...
North Korea rejects olive branch ...
North Korean nuclear symbol destroyed ...
N. Korea hands over nuclear data ... expecting to be removed from the US list of terrorism sponsors in return.
But that move has been delayed amid wrangling over how to verify the North's declaration.
The North has also threatened to restore facilities at its main Yongbyon plant - where the main cooling tower was spectacularly demolished in late June in a symbol of Pyongyang's commitment to disarmament.
'Action for action'
"As the US side failed to keep its own side of the agreement, we cannot but take the following measures under the principle of action for action," the foreign ministry spokesman told the KCNA, according to AFP news agency.
"First, we've decided to stop the denuclearisation process that has been under way in accordance with the 3 October agreement. This measure already took effect on 14 August and relevant parties have already [been] informed.
"Second, we will consider restoring the Yongbyon facilities to their original state in accordance with strong demands from our relevant agencies."
US State Department spokesman Sean McCormack, travelling with Secretary Condoleezza Rice in Jerusalem, said he had no immediate comment on the KCNA report, according to Reuters news agency.
(BBC)
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