North Korea is denying allegations that it has helped Iran to develop nuclear weapons.
North Korea's official media said Friday that unspecified "dishonest forces" have spread rumors of a nuclear link between the two countries.
Some South Korean and Western media reported this month that Tehran received help from Pyongyang in nuclear arms development.
Seoul's Yonhap News Agency said earlier this week that North Korea has sent hundreds of nuclear experts to Iran. It cited an unnamed diplomatic source.
The North's official Korean Central News Agency said such allegations amount to "nonsense."
Iran denies it is developing nuclear weapons. A recent U.N. report says some secret aspects of its nuclear energy program are specific to weapons development.