Iran and North Korea have signed a scientific and technological co-operation agreement, bringing the two nations deeply at odds with the US closer together.
Iranian state TV did not provide further details on the document but said it will include setting up joint scientific and technological laboratories and exchange of scientific teams between the two countries.
The deal also involves the transfer of technology in the fields of information technology, energy, environment, agriculture and food.
Any technical accord between Pyongyang and Tehran is likely to raise suspicions in the West.
The US has repeatedly accused North Korea of providing Iran with advanced missiles capable of targeting Western European capitals.
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Last year, Iran denied a UN panel report saying that North Korea and Iran appear to have been regularly exchanging ballistic missiles, components and technology in violation of UN sanctions.
Iran's state TV said the agreement was signed in Tehran in the presence of Iranian President Mahmoud Ahmadinejad and North Korea's nominal head of state, Kim Yong-nam, by Iran's Minister of Science, Research and Technology Kamran Daneshjoo and North Korea's Foreign Minister Pak Ui-chun.
Iran's Supreme Leader Ayatollah Ali Khamenei told Kim, president of the Presidium of the Supreme People's Assembly, that North Korea and Iran have "common enemies".
"Arrogant powers don't tolerate independent governments," Khamenei told Kim. "In the march towards great goals, one should be serious, and pressures, sanctions and threats should not cause any crack in determination."
In a separate meeting, Ahmadinejad said Kim's visit would have a "great impact on strengthening bilateral ties, expanding co-operation and boosting the anti-hegemonic front".
Both countries are bitter enemies of the US and the West.
Iranian and North Korean officials have said in the past that their nations are in "one trench" in the fight against the Western powers.