North Korea says it is to immediately reactivate a nuclear programme the US suspects was being used to develop weapons.
A North Korean Foreign Ministry spokesman confirms they will revive a Soviet-designed nuclear reactor and resume construction of other nuclear facilities to supply desperately needed power.
The move has raised fears of a nuclear crisis in the region.
The programme was suspended under a 1994 deal with the US, averting a possible war on the Korean Peninsula.
Experts say North Korea could quickly extract enough plutonium from its old facilities to make several nuclear weapons.
But the official says they were obliged to revive the programme because of the US-led decision to suspend annual oil shipments of 500,000 tons to the North.
The shipment of oil was designed to pressure North Korea to give up a more recent nuclear programme based on uranium enrichment.
The United States says the uranium-based programme violated a nuclear arms control clause in the 1994 Agreed Framework.
"The prevailing situation compelled the (North Korean) government to lift its measure for nuclear freeze... and immediately resume the operation and construction of its nuclear facilities to generate electricity," the Foreign Ministry said.
"Our country faced an immediate problem in electricity generation because the United States has virtually abandoned its obligations," he added.