North Korea said Thursday that the 1994 nuclear agreement with the United States is void following a U.S. decision to suspend deliveries of fuel oil.

"Now that the U.S. unilaterally gave up its last commitment under the framework, the DPRK (North Korea) acknowledges that it is high time to decide upon who is to blame for the collapse of the framework," a North Korean Foreign Ministry spokesman was quoted as saying by the North's official news agency.

Under the 1994 deal, North Korea agreed to shut down its plutonium-based nuclear program, suspected of being used to build atomic bombs, in return for two light-water nuclear reactors and 500,000 tons of fuel oil a year until the reactors are built.

But the North in October told visiting U.S. diplomats that it had a uranium enrichment program to build nuclear bombs — an admission that Washington considered a violation of the agreement.

The United States and its allies, including Japan and South Korea, decided earlier this month to suspend oil shipments to punish the North for the nuclear program.

"The DPRK had exercised its forbearance to the full," the unidentified spokesman was quoted as saying by the Korean Central News Agency.

The North has tried to salvage the agreement by proposing to give up its nuclear program if Washington signs a nonaggression treaty with it, the spokesman said.

The United States has ruled out any talks unless the North first scraps the nuclear program.

"But the U.S. responded to the DPRK proposal for concluding a nonaggression treaty with a decision to stop supplying heavy oil to the DPRK," the spokesman was quoted as saying.

The decision is a "wanton violation" of the agreement, he said.

The Korean Peninsula Energy Development Organization, a U.S.-led international consortium, has been building modern reactors to replace Soviet-designed reactors that could supply weapons-grade plutonium. Construction is far behind schedule.

Citing the delays, North Korea has maintained that the United States first broke the pact.

North Korea's biggest ally, China, urged the two sides to salvage the deal.

The agreement "is useful in realizing a nuclear-free Korean Peninsula," Chinese Foreign Ministry spokesman Kong Quan said. "China hopes that the relevant parties can carry out their obligations."