North Korea said on Wednesday its new uranium enrichment plant is designed solely to produce energy, hitting back at the United States for questioning its purpose.
Ruling communist party newspaper Rodong Sinmun said construction of a light water reactor is "actively underway".
"To ensure fuel supply to the reactor, a modern uranium enrichment plant equipped with thousands of centrifuges is in normal operation," it said, reiterating claims first made early this month.
The nuclear-armed North disclosed the plant to visiting US experts last month, heightening regional security fears. US officials and experts have said it could easily be converted to produce weapons-grade uranium.
The US State Department has said the North has "at least one other" uranium enrichment site in addition to the one it disclosed.
The North shut down its elderly plutonium-producing reactor under a six-nation disarmament deal, but it quit the six-party forum in April 2009 and staged a second nuclear test a month later.
The uranium plant gives it a potential second way of making atomic bombs.
"Development of peaceful nuclear energy is a legitimate right of developing countries and the right to use nuclear energy should not be reserved only for a few countries," Rodong said.
"Some powers with faulty mind including the US are taking issue with our peaceful nuclear activities and plotting to put pressure and impose sanctions on us."
The newspaper blamed the US for failing to honour a 1994 accord to build light-water reactors for the North, in exchange for the shutdown of the plutonium-producing reactor.
The deal broke down in 2002 after the US accused the North of running a secret enriched uranium programme. The reactors were never completed.
"Had the US kept its promise and completed the construction of light-water reactors for us, the nuclear issue on the Korean peninsula would not have developed into such a complex situation," the paper said.
Regional unease sparked by the nuclear report intensified after the North shelled a border island last month, killing four South Koreans.
According to US troubleshooter Bill Richardson, who visited Pyongyang this month, the North has offered to permit the return of UN nuclear inspectors and dispose of fuel rods outside the country.
The apparent concessions have not been officially announced.