The United States said energy aid to North Korea had been suspended, prompting Pyongyang to threaten to slow down the disablement of its main nuclear facility, further jeopardising a six-party deal.
Pressure mounted on North Korea today after this week's failed talks in Beijing, with the leaders of Japan and South Korea condemning the reclusive state for being uncooperative.
State department spokesman Sean McCormack said all five countries negotiating with North Korea - Japan, Russia, China, the United States and South Korea - had agreed that future fuel shipments would not go forward until there was progress on a so-called verification protocol with Pyongyang.
"This is an action-for-action process," Mr McCormack told reporters in Washington. "Future fuel shipments aren't going to move forward absent a verification regime ... they (the North Koreans) understand that."
North Korea's foreign minister Kim Kye-gwan was quoted by Kyodo news agency as telling reporters in Beijing that Pyongyang would "probably adjust the pace of disablement at nuclear facilities if (the aid) is suspended".
Multilateral talks in Beijing with North Korea failed on Thursday to break an impasse on checking Pyongyang's nuclear declarations, scuppering the Bush administration's hopes for a diplomatic success before it hands over to president-elect Barack Obama on January 20th.
Meanwhile, Japanese prime minister Taro Aso and South Korean president Lee Myung-bak condemned Pyongyang for its uncooperative stance in the talks in Beijing.
Mr Aso and Mr Lee met in southern Japan today ahead of a rare trilateral summit with Chinese premier Wen Jiabao at which the global financial crisis that is battering their economies will top the agenda.
"Both leaders from the two countries expressed their regret that North Korea showed an uncooperative attitude toward joint efforts by the other participating countries (in the talks)," South Korea's presidential office said in a statement.
A subsequent statement issued after talks between Mr Lee and Mr Wen was less critical of the North, saying only that the two leaders had expressed regret that the talks failed to produce an agreement.
Under an agreement last year, up to 1 million tonnes of heavy fuel aid was promised to energy-starved North Korea as a reward for progress on denuclearisation. Countries outside the five-nation group also have volunteered to supply North Korea with energy as a reward.
By mid-November North Korea had received about half of the amount promised by the five and the United States has provided about 200,000 tons of that, the state department said.
An unspecified amount of fuel was delivered this month by Russia and will finish being offloaded in North Korea next week, state department spokesman Robert McInturff told Reuters.
But Mr McCormack said Russia had made clear in this week's talks in Beijing that any future shipments would not be made until North Korea agreed to the verification protocol.
Reuters