North Korea on Saturday dismissed speculation it was helping Iran develop its atomic programmes, insisting it was behaving as a responsible nuclear state.
"In a bid to mislead public opinion, some Western media recently spread the rumour that the DPRK is cooperating with Iran in nuclear development," the North's KCNA news agency quoted an unnamed Foreign Ministry spokesman as saying.
The DPRK or Democratic People's Republic of Korea is the official name of the communist state.
"Their assertion is nothing but a sheer lie and fabrication intended to tarnish the image of the DPRK by charging it with nuclear proliferation."
North Korea has been under sanctions since the UN Security Council voted to ban military supplies and weapons shipments — sanctions already imposed by the United States — after Pyongyang carried out its first nuclear test in October.
The Security Council also voted unanimously last year to impose sanctions on Iran's trade in sensitive nuclear materials and technology to try to stop enrichment work that could be used to make atomic weapons.
"As solemnly declared more than once by the DPRK, it will continue to sincerely honour its duty it had assumed before the international community in the field of nuclear non-proliferation as a responsible nuclear weapons state," the spokesman said.
Separately, US officials will resume talks with their North Korean counterparts over US financial curbs against Pyongyang on January 30 in Beijing, a Treasury Department spokeswoman said on Friday.
Six-way talks aimed at luring the North to abandon its nuclear programmes are also expected to resume in early February.