North Korea has said it can "never dismantle" its nuclear arsenal while US policy towards it remains hostile.
North Korean nuclear facilities have been the focus of talks
Pyongyang also accused the US of "double standards", saying it had aided nuclear experiments by South Korea.
North Korea suspended talks aimed at nuclear disarmament earlier this month after the disclosure that South Korea had secretly violated nuclear accords.
The US, Japan, China, Russia and South Korea have been negotiating with North Korea to reduce its nuclear capability.
South Korea has said its efforts to extract plutonium and enrich uranium were undertaken purely for civilian purposes.
Mohamed ElBaradei, the head of the UN's atomic agency, meanwhile praised Seoul for co-operating with an inquiry into its nuclear experiments.
A UN team is to arrive in Seoul on Sunday to scrutinise its nuclear disclosures.
South Korea shocked observers on 2 September by admitting its scientists had taken part in small experiments to yield materials that could be used in processes leading towards building nuclear weapons.
The statement by North Korean news agency, KCNA, reiterated a refusal to continue disarmament talks and accused the US of stoking an arms race in the region.
"South Korea's clandestine nuclear experiments go to prove that the US double standards are a fundamental factor of the nuclear proliferation," it said.
Talks could not be resumed, the agency said, "unless the US drops its hostile policy based on double standards towards [North Korea]."
Disarming Pyongyang's "nuclear deterrent force" was also out of the question, KCNA said.
Long-running talks aimed at encouraging North Korea to surrender some of its nuclear weapons in exchange for aid and guarantees of security have made little progress so far.