"One example of the cooperation between the two states took place at the beginning of the 1980s, when Iran agreed to fund the reverse engineering of the Scud-B missile in exchange for the option to purchase production models," the report said.

The report said the cooperation was spawned by the Iran-Iraq war, which lasted from 1980 to 1988, and converted Teheran into one of North Korea's best missile clients.

By 1984, North Korea had produced and flight-tested an indigenous version of the Scud-B. During the following year, the report said, Pyongyang obtained an Iranian commitment to fund missile development and production in exchange for an option by Teheran to purchase North Korean missiles.

Iran used its crude oil revenues to finance North Korea's ballistic missile programs, including the medium-range Scud C, tested in 1991 in the Iranian city of Qom. Soon, Teheran obtained data from North Korea's Hwasong-6, which served as the model for Iran's Shihab-2 medium-range missile, with a range of 700 kilometers.

The report said North Korea appeared ready to use Iran's Lut Desert for the launch of the No Dong-1 in 1993. But the test was cancelled, probably due to international pressure.

In 1998, Teheran was believed to have shared test data with North Korea regarding the Shihab-3 intermediate-range missile. The report said Russian assistance to Iran's missile program in metallurgy and other fields was also believed to have benefited Pyongyang's own missile programs.

"Such cooperation not only increases North Korea's domestic export, but also allows Pyongyang to share information and benefit from missile experiments in Iran while avoiding political costs of conducting flight tests on home ground," the report said. "Furthermore, the partnership contributes in advancing North Korean missile sales to other customers in the Middle East, such as Syria and Egypt."

Iran and North Korea have also engaged in nuclear cooperation over the last 20 years. The two countries have exchanged technical delegations and both of them visited Pakistan. Iran and North Korea also obtained nuclear expertise and components from the Pakistani nuclear smuggling network led by Abdul Qadeer Khan.

The report said Iran cooperated in the North Korean nuclear test in October 2006.

"Foreign intelligence sources even stated that the North Korean nuclear program was partially funded by Iran," the report said. "The increase in Iranian financial assistance to the North Korean nuclear program, in conjunction with a decrease in other foreign assistance to that country, has made Iran an important ally to North Korea."