According to a study by the International Institute for Strategic Studies (IISS), North Korea's weapons programmes are now benefiting from technology from Iran.
Pyongyang also possesses technology that would enable Iran's uranium enrichment programme to increase its output. However concrete evidence that North Korea has supplied the Iranians with its superior equipment has not been uncovered by IISS.
The disclosure marks a disturbing escalation in the race for nuclear weapons technology by the two states which are seen to present the biggest threat to global security.
Mark Fitzpatrick, the IISS expert on weapons proliferation, said North Korea possessed a technological edge over Iran in making nuclear equipment.
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It was capable of manufacturing high strength steel that Iran has been unable to manufacture. Iran has instead relied on carbon fibre materials that are less reliable.
"What previously had been a one way flow of North Korean missile technology to Iran is now going two ways," he said. "North Korea may be self-sufficient in its uranium programme and there are some areas where Iran can't produce equipment that North Korea has the capacity to produce."
The emergence of a North Korean "comparative advantage" over Iran in uranium enrichment has caught experts by surprise. Iran has been working for 20 years on manufacturing advanced centrifuges that enrich uranium to weapons grade. However North Korea has make the breakthrough to produce advanced machines where Iran had failed.
The IISS's fears over North Korea's activities are widely shared by defence experts.
"North Korea has been assisting Iran in going forward with its nuclear programme," said Bruce Bennett, the senior defence analyst at the Rand Corporation, a US think tank. "North Korea has been providing help to Iran with missile technology and testing (nuclear) triggering devices while Iran has only more recently done that kind of thing."
North Korea's weapons technology is the regime's main source of foreign earnings and the country has supplied Iran, Syria, Burma and Libya with its latest equipment.
"Not only has it developed nearly the full array of weapons of mass destruction, it has been willing to sell them and its missiles and conventional arms to any would-be buyer," Mr Fitzpatrick said.
The report said it also appeared that Iran has been able to develop more sophisticated versions of North Korea's No-dong long range missiles.
Recent television broadcasts of Pyongyang military parades showed North Korean No-dong 2 missiles with the same "baby-shaped" nose cone that Iran has fitted on its Ghadr-1.
The modified nose on the Ghadr-1 has been at the root of fears that Iran was attempting to develop nuclear capable missiles.
North Korea herditary Communist leadership has growing increasing reliant on its weapons arsenal and nuclear capabilities to secure its future. A regime that has traditionally defied UN sanctions and diplomatic pressure to supply defence equipment to rogue states is now facing an unstable future as its leadership passes to a new generation.
Kim Jong-il, the country's ageing leader has said he would pass power to his son, Kim Jong-un in an open-ended transistion that has increase uncertainty in surrounding countries.
The younger Kim's lack of military experience and the promotion of other senior members of the ruling family, including the Dear Leader's sister, Kim kyong-hui and her husband Jang Song-thaek, has raised the rise of a power struggle breaking out.
"North Korea is a failing state. Its economy is very poor, it is not producing enough to feed its people, a refugee problem of people trying to flee to China - all at the same time as it is trying to turn over to another dynastic succession," Mr Bennett said. "It is a dangerous state and one capable of taking large risks."
The IISS said the danger that the regime could unravel should not be ignored.
The most benign scenario was that China would take the regime on as protectorate and engineer Chinese style economic reforms.
Under that scenario, the best case outcome was that Beijing would engineer an eventual reunification with South Korea.
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